Removes version constraint for lxml

[duck-nukem]

Should fix #659

Proposed changes

Eases constraint on lxml as python3-saml 1.5.0 should no longer require anything before 4.7.0 and it'd allow users of python-social-auth to mitigate CVE-2021-43818 by upgrading to a more recent version

Types of changes

Please check the type of change your PR introduces:

• 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): Dependency update

Checklist

Put an x in the boxes that apply. You can also fill these out after creating
the PR. If you're unsure about any of them, don't hesitate to ask. We're here to
help! This is simply a reminder of what we are going to look for before merging
your code.

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

No relevant changes to python files at this time

[nijel]

The CI environment will now need adjustment to avoid installing lxml from binaries, as described in https://github.com/SAML-Toolkits/python3-saml#note. Do you have a clue how to do that easily inside tox?

[duck-nukem]

Thanks for the pointer - don't know yet, but I'll do some research and will update the PR. I'll also try running these tests locally to catch issues earlier

[codecov]

Codecov Report

Merging #738 (876d6e4) into master (90a0652) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #738   +/-   ##
=======================================
  Coverage   77.21%   77.21%           
=======================================
  Files         323      323           
  Lines        9810     9810           
  Branches     1051     1051           
=======================================
  Hits         7575     7575           
  Misses       2080     2080           
  Partials      155      155           

Flag	Coverage Δ
unittests	77.21% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[nijel]

Merged, thanks for your contribution!