loader.pypi.model: Log when encountering unexpected release scheme

Example:

['0.1.0.dev0', '0.1.0.dev1', '5.15.0', '5.15.0.dev0', '5.15.0.dev1',
'5.15.0.dev2', '5.15.0.dev3', '5.15.1', '5.15.2', '5.30.0', '5.30.1',
'5.30.2']