fix testProj4Version for Proj.proj_version being an integer

[cjmayo]

ERROR: testProj4Version (__main__.BasicTest)
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Traceback (most recent call last):
  File "test/test.py", line 16, in testProj4Version
    assert re.match(r"\d+\.\d+", awips221.proj_version)
  File "/usr/lib/python3.7/re.py", line 173, in match
    return _compile(pattern, flags).match(string)
TypeError: expected string or bytes-like object

[snowman2]

Oh man. Thanks for catching this! Wouldn't be a proper release without an issue with it :).