Replace a few more uses of virtualenv with venv

[yarikoptic]

No description provided.

[christian-monch]

Thanks for the patches. Left a comment regarding python versions

[mih]

Just a brief comment: I think it would be more sensible to have this PR against the extension template. The load on the CI would be less, and it will need to be done there anyways.

[yarikoptic]

worth doing there too but I guess it is not to be merged here anyways:

❯ git merge gh-template/main
Auto-merging .appveyor.yml
CONFLICT (content): Merge conflict in .appveyor.yml
Auto-merging .codespellrc
CONFLICT (add/add): Merge conflict in .codespellrc
Auto-merging .github/workflows/docbuild.yml
CONFLICT (content): Merge conflict in .github/workflows/docbuild.yml
Auto-merging .github/workflows/test_crippledfs.yml
CONFLICT (content): Merge conflict in .github/workflows/test_crippledfs.yml
Auto-merging CONTRIBUTING.md
CONFLICT (add/add): Merge conflict in CONTRIBUTING.md
Auto-merging README.md
CONFLICT (content): Merge conflict in README.md
Auto-merging changelog.d/scriv.ini
CONFLICT (add/add): Merge conflict in changelog.d/scriv.ini
Auto-merging changelog.d/templates/new_fragment.md.j2
CONFLICT (add/add): Merge conflict in changelog.d/templates/new_fragment.md.j2
CONFLICT (modify/delete): datalad_helloworld/__init__.py deleted in HEAD and modified in gh-template/main.  Version gh-template/main of datalad_helloworld/__init__.py left in tree.
CONFLICT (modify/delete): datalad_helloworld/hello_cmd.py deleted in HEAD and modified in gh-template/main.  Version gh-template/main of datalad_helloworld/hello_cmd.py left in tree.
Auto-merging datalad_next/_version.py
Auto-merging docs/source/conf.py
CONFLICT (content): Merge conflict in docs/source/conf.py
Auto-merging readthedocs.yml
CONFLICT (add/add): Merge conflict in readthedocs.yml
Auto-merging setup.cfg
CONFLICT (content): Merge conflict in setup.cfg
Automatic merge failed; fix conflicts and then commit the result.

[yarikoptic]

apparently needs still to be installed for Ubu20... will add here

[ "x$PY" != x ] && . ${HOME}/venv${PY}/bin/activate || python3 -m venv ${HOME}/dlvenv && . ${HOME}/dlvenv/bin/activate; ln -s "$VIRTUAL_ENV" "${HOME}/VENV"
The virtual environment was not created successfully because ensurepip is not
available.  On Debian/Ubuntu systems, you need to install the python3-venv
package using the following command.
    apt install python3.8-venv
You may need to use sudo with that command.  After installing the python3-venv
package, recreate your virtual environment.
Failing command: ['/home/appveyor/dlvenv/bin/python3', '-Im', 'ensurepip', '--upgrade', '--default-pip']
ln: failed to create symbolic link '/home/appveyor/VENV' -> '': No such file or directory
Command exited with code 1
Running "on_finish" scripts
while [ -f ~/BLOCK ]; do sleep 5; done
Build failed

[mih]

I appreciate the enthusiasm. But all the energy here is spent on fixing something that is not broken.

I do pull in changes from the template.