Bump filelock from 3.18.0 to 3.20.3

Bumps [filelock](https://github.com/tox-dev/py-filelock) from 3.18.0 to 3.20.3.
- [Release notes](https://github.com/tox-dev/py-filelock/releases)
- [Changelog](https://github.com/tox-dev/filelock/blob/main/docs/changelog.rst)
- [Commits](tox-dev/filelock@3.18.0...3.20.3)

---
updated-dependencies:
- dependency-name: filelock
  dependency-version: 3.20.3
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]