[BUG] Fix importlib resources/metadata on older Python versions

[melroy89]

Trying to fix #153...

• Add importlib-metadata & importlib-resources as dependencies
• Check on specific Python version regarding the importlib resources (python v3.10 or higher) in order to have files() working
• importlib_metadata should now also work on Python version before 3.8
• Remove obsolete MANIFEST.in file

[jayvdb]

If you do this, you need to specify a minimum version of PyPI package importlib_resources as a dependency

[melroy89]

I changed it a bit more. I added an explicit check for Python 3.10 and higher: https://github.com/fake-useragent/fake-useragent/pull/154/files#diff-eaceb65d44c0eb2ed1b5108e3e0863edd4c31e7d16d3f7ac5e041ae70b87ce8bR13

Also I added the dependency only for Python lower than 3.10:

https://github.com/fake-useragent/fake-useragent/pull/154/files#diff-50c86b7ed8ac2cf95bd48334961bf0530cdc77b5a56f852c5c61b89d735fd711R13

I also noticed that the unit tests are running much faster now. Most likely because it's actually using the local data as it should be across all Python versions 👍🏽 .