Install babel when checking apprise and Sphinx

[AlexWaygood]

Babel is py.typed these days, and both projects list it as a dependency:

• https://github.com/caronc/apprise/blob/768b38434b99a32b178af497723ef80146e71228/dev-requirements.txt#L7
• https://github.com/sphinx-doc/sphinx/blob/b0fe7301460cac99755d12a68194b57f0939b13f/pyproject.toml#L67