chore(cargo): bump proptest from 1.2.0 to 1.3.1

Bumps [proptest](https://github.com/proptest-rs/proptest) from 1.2.0 to 1.3.1.
- [Release notes](https://github.com/proptest-rs/proptest/releases)
- [Changelog](https://github.com/proptest-rs/proptest/blob/master/CHANGELOG.md)
- [Commits](proptest-rs/proptest@v1.2.0...v1.3.1)

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

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