sagemathgh-37446: Add dependency groups to pyproject.toml

    
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Following [PEP 735](https://peps.python.org/pep-0735/#canonical-names-
of-dependencies-and-dev-el-split-packages), add a few groups of
dependencies that one usually needs while developing sage (e.g. for
tests or docs).

This info will then be used to generate the conda lock files and once
support for PEP 735 is more widespread other tools will be able to use
the metadata as well. Eg, once pypa/pip#12963
is implemented one can install all test dependencies with `pip install
--groups test`.

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URL: sagemath#37446
Reported by: Tobias Diez
Reviewer(s): Dima Pasechnik

pyproject.toml

@@ -90,8 +90,8 @@ platforms = [
     'osx-64', 'linux-64', 'linux-aarch64', 'osx-arm64'
 ]
 
-[external]
 # External dependencies in the format proposed by https://peps.python.org/pep-0725
+[external]
 build-requires = [
   "virtual:compiler/c",
   "virtual:compiler/cpp",
@@ -152,4 +152,23 @@ dependencies = [
   "pkg:generic/tachyon",
   "pkg:generic/sagemath-polytopes-db",
   "pkg:generic/sagemath-elliptic-curves",
+  "pkg:generic/sagemath-graphs",
+]
+
+[dependency-groups]
+test = [
+  "pytest",
+  "pytest-xdist",
+  "coverage",
+]
+docs = [
+  "sphinx", 
+  "sphinx-inline-tabs", 
+  "furo",
+]
+lint = [
+  "relint",
+  "ruff",
+  "pycodestyle",
+  "flake8-rst-docstrings",
 ]