🧪 TESTS: Add testing for Python 3.9 and pygments versions

[foster999]

Adds tesing for:

• Python version 3.9
• a range of pygments versions, in response to Pygments 2.10 tets failures #134
• latest sphinx version above 4 (was previously fixed to ==4.0.0b1)

[codecov]

Codecov Report

Merging #135 (86d7a1a) into master (0f185f4) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #135   +/-   ##
=======================================
  Coverage   92.23%   92.23%           
=======================================
  Files           2        2           
  Lines         219      219           
=======================================
  Hits          202      202           
  Misses         17       17           

Flag	Coverage Δ
pytests	92.23% <ø> (ø)

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[foster999]

Hi @humitos, I've just realised that the new test using app.set_html_assets_policy("always") wasn't getting hit because our sphinx testing version was fixed below 4.1 😅

I've changed that here to test the latest between 4 and 5, and the new test is now failing. It looks like the JS asset isn't being included when the config option is set. I'm stuck on why this might be, any thoughts?

[humitos]

Hi @humitos, I've just realised that the new test using app.set_html_assets_policy("always") wasn't getting hit because our sphinx testing version was fixed below 4.1 sweat_smile

I remember running the test and failing locally. Then, after some debugging, I was able to fix it (see this comment #127 (comment) where we talked about this failing test)

I'm not sure how the .html/.xml files added to this PR were generated (I didn't upload them in my original PR). So, I'm guessing there is something there that may be conflicting. I'll take a look next week.

[foster999]

Thanks, I'd totally forgotten about that. Working fine with a copy of the test source files now 😄

[humitos]

Excellent! Happy you already fixed it! 💪