chore(deps-dev): update mypy requirement from >=1.19.1,<1.20 to >=2.0.0,<3.0.0 and fix and adjust configuration and fix code according to the newly uncovered type errors

[jenstroeger]

Summary

The current version of mypy is v2.3.0 although PR #1396 stalls at v1.20.2 — there’s no Dependabot for v2? But even so, that PR fails because of how mypy is configured and how it’s used by pre-commit. Related issue discussions are python/mypy#13916 and python/mypy#21769.

This PR is in Draft so we can discuss and fix a few type issues.

Description of changes

1. Update mypy to its most recent version v2.3.0.
2. Fix the configuration as per Using mypy via pre-commit python/mypy#13916.
3. Fix the type issues discovered by above changes 1. and 2.

Related issues

n/a

Checklist

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• I have updated the relevant documentation, if applicable.
• I have tested my changes and verified they work as expected.

[jenstroeger]

Thanks @behnazh-w for running CI: please take a look at the failing type checks here. Shall I go ahead and address these issues or do you want to do that yourself?