Allow users to specify version information for the `required_plugins` INI key

[gnikonorov]

Building off of #7305, we should allow users to specify the required versions of the plugins they would like to make required. This should be implemented as defined in PEP 440, and should be optional after each plugin name in the list of required plugins.

For example:

[pytest]
required_plugins = pugin1===1.0.0 plugin2<=5.6.1 plugin3 plugin4~=3.2.1

[gnikonorov]

Thoughts @nicoddemus and @RonnyPfannschmidt?

[nicoddemus]

Yep the description is accurate, thanks. We should use packaging to match the versions.

[gnikonorov]

Thanks for suggesting packaging @nicoddemus, I’ll use it