Update py and cryptography

[epenet]

Update dependencies for January release of safety-db

cryptography = "^3.3.1" # safety (pyup.io-39252)
Cryptography 3.3 no longer allows loading of finite field Diffie-Hellman parameters of less than 512 bits in length. This change is to conform with an upcoming OpenSSL release that no longer supports smaller sizes. These keys were already wildly insecure and should not have been used in any application outside of testing.

py = "^1.10.0" # safety (pyup.io-39253 / CVE-2020-29651)
A denial of service via regular expression in the py.path.svnwc component of py (aka python-py) through 1.9.0 could be used by attackers to cause a compute-time denial of service attack by supplying malicious input to the blame functionality. See CVE-2020-29651.

[cjolowicz]

Thanks 👍

I decided to do this in #224 instead, to avoid the unrelated bump to coverage (some Poetry quirk?) and to avoid adding direct dependencies (updated only the lock file instead).