Add SSL_CTX_set_min_proto_version/SSL_CTX_set_max_proto_version bindings (#985)

* add Context.set_*_proto_version, fix #860

* docs: add new openssl tls methods

* accept the fact that nothing can be taken for granted

* bump minimum required cryptography version to 3.3

* drop support for Python 3.5

* use binary wheels for cryptography

* Revert "use binary wheels for cryptography"

This reverts commit 91a04c612ed1d0dd9fd541dfefe21cac7c25b1c1.

* docker ci: compile cryptography with rust
8 files changed