This fixes the following class of error messages by automatically installing a PEP 561 stub package if available :

>>> Lint for contrib/teamcity/build-configurations.py:

   Error  () mypy found an issue:
    Library stubs not installed for "yaml"  [import]

arc lint --everything

Add import toml in some python file and check that it does not cause any new error, and that the python package types-toml is installed after running arc lint (pip list | grep types)