Update proptest requirement from 0.7 to 0.8
Update proptest requirement from 0.7 to 0.8

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/0.8.7)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
spacejam/sled,spacejam/sled,spacejam/sled