python-blosc2 release procedure

Preliminaries

Check that VERSION file contains the correct number.
Make sure that the c-blosc2 submodule is updated to the latest version (or a specific version that will be documented in the RELEASE_NOTES.md):
```
cd blosc2/c-blosc2
git checkout <desired tag>
git pull
cd ../..
git commit -m "Update c-blosc2 sources" blosc2/c-blosc2
git push
```
Make sure that the current master branch is passing the tests in continuous integration.

Build the package and make sure that:

PYTHONPATH=. python -c "import blosc2; blosc2.print_versions()"

is printing the correct versions.

Make sure that RELEASE_NOTES.md and ANNOUNCE.rst are up to date with the latest news in the release.

Commit the changes:

git commit -a -m "Getting ready for release X.Y.Z"
git push

Double check that the supported Python versions for the wheels are the correct ones (.github/workflows/cibuildwheels.yml). Add/remove Python version if needed. Also, update the classifiers field for the supported Python versions.
Check that the metainfo for the package is correct:
```
python -m build --sdist
twine check dist/*
```

Create a (signed, if possible) tag X.Y.Z from main. Use the next message:
```
git tag -a vX.Y.Z -m "Tagging version X.Y.Z"
```
Push the tag to the github repo:
```
git push --tags
```
Go to Blosc/blogsite repo and click on the Re-run all jobs button to regenerate the documentation and check that it has been correctly updated in https://www.blosc.org.

Do an actual release in github by visiting: https://github.com/Blosc/python-blosc2/releases/new Add the notes specific for this release. This will upload the wheels to PyPI too.
Check that the package (and wheels!) have been uploaded to PyPI (they should have been created when GHA would finish the tag trigger): https://pypi.org/project/blosc2/

Check that the packages and wheels are sane:

python -m pip install blosc2 -U
cd tests
python -c"import blosc2; blosc2.print_versions()"
pytest

Send an announcement to the Blosc list. Use the ANNOUNCE.rst file as skeleton (or possibly as the definitive version). Start the subject with ANN:.
Announce in Twitter via @Blosc2 account and rejoice.

Change back to the actual python-blosc2 repo:
```
cd $HOME/blosc/python-blosc2
```
Create new headers for adding new features in RELEASE_NOTES.md add this place-holder:

XXX version-specific blurb XXX
Edit VERSION in master to increment the version to the next minor one (i.e. X.Y.Z --> X.Y.(Z+1).dev0).

Commit your changes with:

git commit -a -m "Post X.Y.Z release actions done"
git push

That's all folks!