requirements/docs.txt: Use current versions of Jinja2 and sphinx

Thanks for submitting a PR!

Please make sure to check for the following items:

[ ] Add unit tests and integration tests where applicable.
If you've added an error code or changed an error code behavior, you should probably add or change a test case file under tests/test_cases/ and add it to the list under tests/test_definitions.py.
If you've added or changed a command line option, you should probably add or change a test in tests/test_integration.py.
[ ] Add a line to the release notes (docs/release_notes.rst) under "Current Development Version".
Make sure to include the PR number after you open and get one.

Please don't get discouraged as it may take a while to get a review.

PyCQA / pydocstyle