Update Python packages

Some of the Python packages used by Krake are not in the latest version. They include (non-exhaustive list, may need to be completed):

• kubernetes-asyncio: 10.* -> 12.* (breaks the test);
• lark-parser: 0.8.* -> 0.10.* (untested);
• python-magnumclient: 2.* -> 3.* (untested);
• webargs: 5.* -> 6.* (breaks the test).

The changes need to be investigated, to see which new feature could be interesting.