Fix import error when running examples in fresh environment

[awaelchli]

What does this PR do?

Fixes a requests import error when running the PyTorch Lightning basic examples from a freshly installed environment.

To reproduce:

conda create -n lightning-fresh python=3.11
conda activate lightning-fresh
pip install lightning
python examples/pytorch/basics/autoencoder.py

Error:

Traceback (most recent call last):
  File "/Users/adrian/repositories/lightning/examples/pytorch/basics/autoencoder.py", line 26, in <module>
    from lightning.pytorch.demos.mnist_datamodule import MNIST
  File "/Users/adrian/repositories/lightning/src/lightning/pytorch/demos/__init__.py", line 1, in <module>
    from lightning.pytorch.demos.transformer import LightningTransformer, Transformer, WikiText2  # noqa: F401
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/adrian/repositories/lightning/src/lightning/pytorch/demos/transformer.py", line 12, in <module>
    import requests
ModuleNotFoundError: No module named 'requests'

---

📚 Documentation preview 📚: https://pytorch-lightning--19431.org.readthedocs.build/en/19431/

cc @Borda

[github-actions]

⚡ Required checks status: All passing 🟢

Groups summary

🟢 pytorch_lightning: Tests workflow

Check ID	Status
pl-cpu (macOS-11, lightning, 3.8, 1.13, oldest)	success	✅
pl-cpu (macOS-11, lightning, 3.10, 1.13)	success	✅
pl-cpu (macOS-11, lightning, 3.10, 2.1)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.8, 1.13, oldest)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.10, 1.13)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.10, 2.1)	success	✅
pl-cpu (windows-2022, lightning, 3.8, 1.13, oldest)	success	✅
pl-cpu (windows-2022, lightning, 3.10, 1.13)	success	✅
pl-cpu (windows-2022, lightning, 3.10, 2.1)	success	✅
pl-cpu (macOS-11, pytorch, 3.8, 1.13)	success	✅
pl-cpu (ubuntu-20.04, pytorch, 3.8, 1.13)	success	✅
pl-cpu (windows-2022, pytorch, 3.8, 1.13)	success	✅
pl-cpu (macOS-12, pytorch, 3.11, 2.0)	success	✅
pl-cpu (macOS-12, pytorch, 3.11, 2.1)	success	✅
pl-cpu (ubuntu-22.04, pytorch, 3.11, 2.0)	success	✅
pl-cpu (ubuntu-22.04, pytorch, 3.11, 2.1)	success	✅
pl-cpu (windows-2022, pytorch, 3.11, 2.0)	success	✅
pl-cpu (windows-2022, pytorch, 3.11, 2.1)	success	✅

These checks are required after the changes to requirements/pytorch/examples.txt, src/lightning/pytorch/demos/transformer.py.

🟢 pytorch_lightning: Azure GPU

Check ID	Status
pytorch-lightning (GPUs) (testing Lightning | latest)	success	✅
pytorch-lightning (GPUs) (testing PyTorch | latest)	success	✅

These checks are required after the changes to requirements/pytorch/examples.txt, src/lightning/pytorch/demos/transformer.py.

🟢 pytorch_lightning: Benchmarks

Check ID	Status
lightning.Benchmarks	success	✅

These checks are required after the changes to requirements/pytorch/examples.txt, src/lightning/pytorch/demos/transformer.py.

🟢 pytorch_lightning: Docs

Check ID	Status
docs-make (pytorch, doctest)	success	✅
docs-make (pytorch, html)	success	✅

These checks are required after the changes to src/lightning/pytorch/demos/transformer.py, requirements/pytorch/examples.txt.

🟢 pytorch_lightning: Docker

Check ID	Status
build-cuda (3.9, 1.13, 11.8.0)	success	✅
build-cuda (3.9, 1.13, 12.0.1)	success	✅
build-cuda (3.10, 2.0, 11.8.0)	success	✅
build-cuda (3.10, 2.1, 12.1.0)	success	✅
build-pl (3.9, 1.13, 11.8.0)	success	✅
build-pl (3.9, 1.13, 12.0.1)	success	✅
build-pl (3.10, 2.0, 11.8.0)	success	✅
build-pl (3.10, 2.1, 12.1.0)	success	✅

These checks are required after the changes to requirements/pytorch/examples.txt.

🟢 mypy

Check ID	Status
mypy	success	✅

These checks are required after the changes to requirements/pytorch/examples.txt, src/lightning/pytorch/demos/transformer.py.

🟢 install

Check ID	Status
install-pkg (ubuntu-22.04, app, 3.8)	success	✅
install-pkg (ubuntu-22.04, app, 3.11)	success	✅
install-pkg (ubuntu-22.04, fabric, 3.8)	success	✅
install-pkg (ubuntu-22.04, fabric, 3.11)	success	✅
install-pkg (ubuntu-22.04, pytorch, 3.8)	success	✅
install-pkg (ubuntu-22.04, pytorch, 3.11)	success	✅
install-pkg (ubuntu-22.04, lightning, 3.8)	success	✅
install-pkg (ubuntu-22.04, lightning, 3.11)	success	✅
install-pkg (ubuntu-22.04, notset, 3.8)	success	✅
install-pkg (ubuntu-22.04, notset, 3.11)	success	✅
install-pkg (macOS-12, app, 3.8)	success	✅
install-pkg (macOS-12, app, 3.11)	success	✅
install-pkg (macOS-12, fabric, 3.8)	success	✅
install-pkg (macOS-12, fabric, 3.11)	success	✅
install-pkg (macOS-12, pytorch, 3.8)	success	✅
install-pkg (macOS-12, pytorch, 3.11)	success	✅
install-pkg (macOS-12, lightning, 3.8)	success	✅
install-pkg (macOS-12, lightning, 3.11)	success	✅
install-pkg (macOS-12, notset, 3.8)	success	✅
install-pkg (macOS-12, notset, 3.11)	success	✅
install-pkg (windows-2022, app, 3.8)	success	✅
install-pkg (windows-2022, app, 3.11)	success	✅
install-pkg (windows-2022, fabric, 3.8)	success	✅
install-pkg (windows-2022, fabric, 3.11)	success	✅
install-pkg (windows-2022, pytorch, 3.8)	success	✅
install-pkg (windows-2022, pytorch, 3.11)	success	✅
install-pkg (windows-2022, lightning, 3.8)	success	✅
install-pkg (windows-2022, lightning, 3.11)	success	✅
install-pkg (windows-2022, notset, 3.8)	success	✅
install-pkg (windows-2022, notset, 3.11)	success	✅

These checks are required after the changes to src/lightning/pytorch/demos/transformer.py, requirements/pytorch/examples.txt.

---

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[codecov]

Codecov Report

Merging #19431 (01a61f1) into master (bc56630) will decrease coverage by 28%.
The diff coverage is 40%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #19431      +/-   ##
==========================================
- Coverage      77%      48%     -28%     
==========================================
  Files         450      442       -8     
  Lines       38072    37923     -149     
==========================================
- Hits        29195    18389   -10806     
- Misses       8877    19534   +10657