[cherry-pick] Fix mypy plugin for 1.4.0 (#5927)

[cdce8p]

Change Summary

Cherry-pick of #5927
Adapted for 1.10.X.

Related issue number

Checklist

• Unit tests for the changes exist
• Tests pass on CI and coverage remains at 100%
• Documentation reflects the changes where applicable
• changes/<pull request or issue id>-<github username>.md file added describing change
  (see changes/README.md for details)
• My PR is ready to review, please add a comment including the phrase "please review" to assign reviewers

Selected Reviewer: @PrettyWood

[cdce8p]

please review

[cdce8p]

#5927 was just merged.

After this PR is merged as well, it would be awesome if 1.10.9 could be released. That would make testing mypy dev versions a bit easier.

[hramezani]

@samuelcolvin Do we plan to prepare a new release for 1.10.x to include this change?

If so, I can handle it.

BTW, it's ready to merge

[cdce8p]

Any update on a 1.10.9 release? The next mypy release (which breaks the 1.10.8 plugin) is currently scheduled for early July (about a month). It would be awesome to have the fix released sooner rather than later to give people enough time to update and make the transition as painless as possible.

[samuelcolvin]

good idea, will do.