Bump fonttools from 4.40.0 to 4.43.0 in /python/alibiexplainer

Bumps [fonttools](https://github.com/fonttools/fonttools) from 4.40.0 to 4.43.0.
- [Release notes](https://github.com/fonttools/fonttools/releases)
- [Changelog](https://github.com/fonttools/fonttools/blob/main/NEWS.rst)
- [Commits](fonttools/fonttools@4.40.0...4.43.0)

---
updated-dependencies:
- dependency-name: fonttools
  dependency-type: indirect
...

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