Bump exchangelib from 5.3.0 to 5.4.0

Bumps [exchangelib](https://github.com/ecederstrand/exchangelib) from 5.3.0 to 5.4.0.
- [Release notes](https://github.com/ecederstrand/exchangelib/releases)
- [Changelog](https://github.com/ecederstrand/exchangelib/blob/master/CHANGELOG.md)
- [Commits](ecederstrand/exchangelib@v5.3.0...v5.4.0)

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

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