Update mypy version to 1.7.1

[LacombeLouis]

Description

Fixing an issue with mypy. #398

Type of change

Please remove options that are irrelevant.

• Bug fix (non-breaking change which fixes an issue)

Checklist

• [x] I have read the contributing guidelines
• [x] I have updated the HISTORY.rst and AUTHORS.rst files
• [x] Linting passes successfully : make lint
• [x] Typing passes successfully : make type-check
• [x] Unit tests pass successfully : make tests
• [x] Coverage is 100% : make coverage
• [x] Documentation builds successfully : make doc

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (614293e) 100.00% compared to head (c240f85) 100.00%. Report is 173 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #399 +/- ## ========================================== Coverage 100.00% 100.00% ========================================== Files 39 39 Lines 4616 4772 +156 Branches 487 792 +305 ========================================== + Hits 4616 4772 +156 ```

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