Add pylint-pytest plugin

[drew2a]

This PR adds the pylint-pytest plugin to the .pylintrc file, enabling additional checkers for pytest. It also includes the pylint-pytest package in the requirements-test.txt file, ensuring it is installed when running tests.

The necessity of adding this plugin emerged from the notable discussion in #7764, where @drew2a proposed the use of pylint-pytest and @qstokkink supported the idea:

Just to repeat - myself and the docs - adding a "name" is not the only way to resolve this. Secondarily, this has nothing to do with Pylint, other than that it will also tell you the same thing. I like the idea of adding pylint-pytest though.

Ref:

• Fix "ValueError: relative path can't be expressed as a file URI" #7764 (review)
• https://github.com/pylint-dev/pylint-pytest

[drew2a]

Unfortunately, it seems not possible to use this plugin with Codacy, as they use preinstalled plugins:

• https://docs.codacy.com/repositories-configure/configuring-code-patterns/#import-patterns
• https://github.com/codacy/codacy-pylint-python3/blob/master/requirements.txt

[drew2a]

I've created a PR to codacy-pylint-python3 to extend the plugin list:

• Add pylint-pytest==1.1.7 to requirements.txt codacy/codacy-pylint-python3#196

Let's wait for the response from the repository maintainers.

[drew2a]

The repository maintainers responded that the requested change was added:

• Bump to version 3.0.3 TS-731 codacy/codacy-pylint-python3#197