Try to fix macOS tests

openlp/core/ui/media/vendor/mediainfoWrapper.py

@@ -25,13 +25,15 @@ on a media file and obtain information related to the requested media.
 """
 from pymediainfo import MediaInfo
 from subprocess import check_output
+import sys
 
 
 class MediaInfoWrapper(object):
 
     @staticmethod
     def parse(filename):
-        if MediaInfo.can_parse():
+        # FIXME: library loading on macOS
+        if sys.platform != 'darwin' and MediaInfo.can_parse():
             return MediaInfo.parse(filename)
         else:
             xml = check_output(['mediainfo', '-f', '--Output=XML', '--Inform=OLDXML', filename])