Update cryptography requirement from >=2.6,<36.0 to >=2.6,<37.0
Updates the requirements on [cryptography](https://github.com/pyca/cryptography) to permit the latest version.
- [Release notes](https://github.com/pyca/cryptography/releases)
- [Changelog](https://github.com/pyca/cryptography/blob/main/CHANGELOG.rst)
- [Commits](https://github.com/pyca/cryptography/compare/2.6...36.0.0)