Replace broken type annotations with type comments

[Vlad-Shcherbina]

Fixes #3635.

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Checklist:

• Create a new changelog file in the changelog folder, with a name like <ISSUE NUMBER>.<TYPE>.rst. See changelog/README.rst for details.
• Target the master branch for bug fixes, documentation updates and trivial changes.
• Target the features branch for new features and removals/deprecations.
• Include documentation when adding new features.
• Include new tests or update existing tests when applicable.

Unless your change is trivial or a small documentation fix (e.g., a typo or reword of a small section) please:

• Add yourself to AUTHORS in alphabetical order;

[nicoddemus]

Thanks @Vlad-Shcherbina!

[coveralls]

Coverage increased (+0.05%) to 92.655% when pulling 58e77f5 on Vlad-Shcherbina:type_comments into 0565a7a on pytest-dev:master.