Build failed, probable dependency version conflict

[mslw]

The latest monthly link check failed with:

ImportError: cannot import name 'environmentfilter' from 'jinja2' (/opt/hostedtoolcache/Python/3.10.2/x64/lib/python3.10/site-packages/jinja2/__init__.py)

Google leads to this issue in Sphinx which says that deprecations in Jinja2 are the cause. Suggested workaround is to pin jinja2 < 3.1 (consistent with the fact that the failed build used 3.1.1, while the last successful used 3.0.3). A proper fix would be to unpin Sphinx itself (currently we have sphinx==2.1.2) and use the latest version, currently 4.5 (which is a big leap).

If readthedocs build fail too, we will need to pin Jinja2, and maybe consider updating Sphinx later on.

[mslw]

Yes, this repeated for handbook build on github actions after a recent PR. Read the docs builds seems unaffected.

The corresponding RTD build succeeded and the handbook has recent changes. Could be because on RTD we use python 3.7 (specified in .readthedocs.yaml) and that affects installed libraries, but I'm not sure.