Bump tuf from 2.1.0 to 3.1.1

Bumps [tuf](https://github.com/theupdateframework/python-tuf) from 2.1.0 to 3.1.1.
- [Release notes](https://github.com/theupdateframework/python-tuf/releases)
- [Changelog](https://github.com/theupdateframework/python-tuf/blob/develop/docs/CHANGELOG.md)
- [Commits](theupdateframework/python-tuf@v2.1.0...v3.1.1)

---
updated-dependencies:
- dependency-name: tuf
  dependency-version: 3.1.1
  dependency-type: indirect
...

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

Author: dependabot[bot]