Bump argon2-cffi from 21.3.0 to 23.1.0 in /backend/paaster

Bumps [argon2-cffi](https://github.com/hynek/argon2-cffi) from 21.3.0 to 23.1.0.
- [Release notes](https://github.com/hynek/argon2-cffi/releases)
- [Changelog](https://github.com/hynek/argon2-cffi/blob/main/CHANGELOG.md)
- [Commits](hynek/argon2-cffi@21.3.0...23.1.0)

---
updated-dependencies:
- dependency-name: argon2-cffi
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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