chore: bump `mypy` from 1.15.0 to 1.16.0 and resolve typing issues (#20900)

* build(deps): bump mypy from 1.15.0 to 1.16.0 in /requirements

Bumps [mypy](https://github.com/python/mypy) from 1.15.0 to 1.16.0.
- [Changelog](https://github.com/python/mypy/blob/master/CHANGELOG.md)
- [Commits](https://github.com/python/mypy/compare/v1.15.0...v1.16.0)

---
updated-dependencies:
- dependency-name: mypy
  dependency-version: 1.16.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

* fix typing

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update fsdp.py

---------

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>