[fix] #113: Support libnacl version from v1.7.2

Change libnacl version
Force libnacl minimum version to v1.7.2

To support Py3.9
https://github.com/saltstack/libnacl/issues/120#issuecomment-721336469
https://github.com/saltstack/libnacl/commit/33b22d2edc86edbb1a2dcb0b902428a40cc5e35b