Improve coverage of dpctl.__init__ file and other service functions

[oleksandr-pavlyk]

Added tests to check DPCTLService_GetDPCPPVersion, dpctl.get_include, and dpctl.__version__.

[coveralls]

Coverage increased (+0.7%) to 67.33% when pulling 0c499ec on coverage-init into 33031a2 on master.

[oleksandr-pavlyk]

@PokhodenkoSA Any idea why this test is failing

    def test___version__():
        dpctl_ver = getattr(dpctl, "__version__", None)
        assert type(dpctl_ver) is str
>       assert "unknown" not in dpctl_ver
E       AssertionError: assert 'unknown' not in '0+unknown'
E         'unknown' is contained here:
E           0+unknown

/usr/share/miniconda/lib/python3.8/site-packages/dpctl/tests/test_service.py:88: AssertionError
=========================== short test summary info ============================
FAILED tests/test_service.py::test___version__ - AssertionError: assert 'unkn...
================= 1 failed, 785 passed, 1051 skipped in 2.56s ==================
Error: Process completed with exit code 1.

I think the expectation for it to not contain "unknown" is reasonable, and addition of this test has caught an actual issue.

[oleksandr-pavlyk]

@PokhodenkoSA Any idea why this test is failing

I think the expectation for it to not contain "unknown" is reasonable, and addition of this test has caught an actual issue.

This is likely caused by using limited depth cloning, specifically use of - fetch_depth: 0 in workflows.

If we rely on git tags for deducing versions of the product, we should do a full checkout.

[oleksandr-pavlyk]

Turns out this has been a regression I introduced nearly at the beginning of 0.9 development cycle. Now fixed, tests should start passing.