Fix incorrect condition for skipping Libcint tests

[msricher]

The current test won't work because it only checks if the build files exist: https://github.com/theochem/gbasis/blob/3a88b8400d17070e2e41e43ab281dea5a109279a/tests/test_libcint.py#L62-L63

It should actually check if a file matching gbasis/integrals/lib/libcint.so* exists, as this is the actual file that will be loaded, and included with gbasis when it is packaged.

This commit fixes the check, so that the libcint tests will only be skipped if Libcint is missing from the actual package.

@leila-pujal

Checklist

• [x] Write a good description of what the PR does.
• [x] Add tests for each unit of code added (e.g. function, class)
• [x] Update documentation
• [ ] Squash commits that can be grouped together
• [ ] Rebase onto master

Type of Changes

	Type
✓	:bug: Bug fix
✓	:sparkles: New feature
✓	:hammer: Refactoring
✓	:scroll: Docs

Related

[leila-pujal]

@msricher, the pytest workflows in github actions don't pass. We get this error:

ERROR tests/test_libcint.py - TypeError: glob() got an unexpected keyword argument 'root_dir'
!!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!
=============================== 1 error in 2.75s ===============================

[msricher]

You're right, that's not a valid option for older Python versions. This fixes it.