Use specific PyKMIP version

[oittaa]

Installing from requirements.txt also makes it possible to use Dependabot in the future. Should help people from #13

[oittaa]

If you want to try TLS 1.3 support and Python 3.12, you can replace the line on requirements.txt with this:

git+https://github.com/oittaa/PyKMIP@d27e7acc329ddf86bbde0489935cb44a4f7d54c8

And then change the Alpine linux version to 3.20 in the Dockerfile.

The unit tests fail since TLS 1.3 and Python 3.12 aren't compatible with all the tests, but my Synology NAS connected to it without issues.

[rnurgaliyev]

Thank you!