chore: downgrade Sphinx to 7.1.2

[lupino3]

This should fix the snapcraft build, which for some reason isn't finding Sphinx 7.2.2

[codecov-commenter]

Codecov Report

Merging #773 (7d1ae27) into master (9cdb265) will not change coverage.
The diff coverage is n/a.

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Additional details and impacted files

@@            Coverage Diff            @@
##             master     #773   +/-   ##
=========================================
  Coverage     51.14%   51.14%           
  Complexity     1447     1447           
=========================================
  Files           249      249           
  Lines          9879     9879           
  Branches       1092     1092           
=========================================
  Hits           5053     5053           
  Misses         4507     4507           
  Partials        319      319           

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[lupino3]

I don't get how it's still trying to install 7.2.2 on GitHub Actions

> Task :pipInstall
[python] .gradle/python/bin/python -m pip install sphinx==7.2.2
	 ERROR: Could not find a version that satisfies the requirement sphinx==7.2.2
	 ERROR: No matching distribution found for sphinx==7.2.2
	 WARNING: You are using pip version 21.0.1; however, version 23.2.1 is available.
	 You should consider upgrading via the '/root/parts/edumips64/build/.gradle/python/bin/python -m pip install --upgrade pip' command.

[lupino3]

I wonder if there is some caching going on. I'll merge the PR and see if it fixes master.

[lupino3]

Yep, working on master: https://github.com/EduMIPS64/edumips64/actions/runs/6132027268/job/16642523230.