deps: Drop support for old Python versions

[nijel]

Proposed changes

Drop support for Python versions not supported upstream.

Types of changes

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• Release (new release request)
• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (PEP8, lint, formatting, renaming, etc)
• Refactoring (no functional changes, no api changes)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Build related changes (build process, tests runner, etc)
• Other (please describe):

Checklist

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• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works

Other information

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[nijel]

@omab This needs changes in branch protection rules. Is there a chance you would grant me permission to perform such changes?

[codecov]

Codecov Report

Merging #817 (f3ee6f8) into master (cf95380) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           master     #817    +/-   ##
========================================
  Coverage   77.80%   77.80%            
========================================
  Files         330      330            
  Lines       10097    10097            
  Branches     1195      681   -514     
========================================
  Hits         7856     7856            
  Misses       2087     2087            
  Partials      154      154            

Flag	Coverage Δ
unittests	77.80% <ø> (ø)

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