security/py-cryptography: Update to 2.0.3

• Update LICENSE section, now Dual-licensed
• Update dependencies and minimum versions
• Enable concurrent Python feature
• Remove upstreamed patch
• Remove version support declaration from pkg-descr

Changelog:

https://cryptography.io/en/latest/changelog/#v2-0-3

PR: 222519
Submitted by: Yasuhiro KIMURA <yasu utahime org>