⬆️ Update proptest requirement to 0.7.1

Updates the requirements on [proptest](https://github.com/altsysrq/proptest) to permit the latest version.
- [Release notes](https://github.com/altsysrq/proptest/releases)
- [Changelog](https://github.com/AltSysrq/proptest/blob/master/CHANGELOG.md)
- [Commits](https://github.com/altsysrq/proptest/commits/0.7.1)

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

Cargo.toml

@@ -38,4 +38,4 @@ skeptic = "0.13"
 env_logger = "0.5"
 mockito = "0.11.0"
 spectral = "0.6.0"
-proptest = "0.6.0"
+proptest = "0.7.1"