Update test cases from upstream, now using pytest

[amotl]

Problem

The test cases have been adjusted to use pytest instead of unittest. The change happened between MLflow 2.10.2 and 2.11.3.

• Update MLflow from 2.10.2 to 2.11.3 #124

Also, a few other spots want to be synchronized.

• tests/test_tracking.py: CrateDB raises different error for dataset schema size validation #261
• tests/test_tracking.py: Add missing attribute-based search test after set_tag #263
• tests/test_tracking.py: Submit get_metric_history on non-existent key bugfix to upstream MLflow #264

Evaluation

It does not mean a regression in runtime behavior, but it will add drag to future maintenance of the code base.

Solution

Migrate test cases to pytest as well, so updates and changes from upstream can be integrated without further ado.