Non convergence error + SNES div tol unlimited

[RemDelaporteMathurin]

Proposed changes

This PR fixes an issue @hhy2022 found when upgrading the V&V book to FESTIM 2.0-beta.0 by removing the test on the SNES DIV TOL

Types of changes

What types of changes does your code introduce to FESTIM?

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Code refactoring
• Documentation Update (if none of the other choices apply)
• New tests

Checklist

• Black formatted
• Unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.87%. Comparing base (5acfcc0) to head (6e69c97).
⚠️ Report is 5 commits behind head on fenicsx.

Additional details and impacted files

@@           Coverage Diff            @@
##           fenicsx    #1049   +/-   ##
========================================
  Coverage    94.87%   94.87%           
========================================
  Files           44       44           
  Lines         3085     3085           
========================================
  Hits          2927     2927           
  Misses         158      158           

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