Missing type hints for 3rd party package warning gets shown more than once per package

[obi1kenobi]

Example duplicates with identical module names:

WARNING: mypy was not able to find type hints for module 'pytest' since it does not seem to be installed in the current environment. Assuming it has no type hints available.
WARNING: mypy was not able to find type hints for module 'pytest' since it does not seem to be installed in the current environment. Assuming it has no type hints available.

Example duplicates with different module names but part of the same package:

WARNING: mypy was not able to find type hints for module 'pyorient' since it does not seem to be installed in the current environment. Assuming it has no type hints available.
WARNING: mypy was not able to find type hints for module 'pyorient.constants' since it does not seem to be installed in the current environment. Assuming it has no type hints available.
WARNING: mypy was not able to find type hints for module 'pyorient.ogm' since it does not seem to be installed in the current environment. Assuming it has no type hints available.

To avoid overwhelming the user with repetitive output, we'd like each package to show up only once regardless of which of their modules or submodules are lacking type hints.