tests/gobject-query.py: make it work on msys2/win32

For unclear reasons, universal_newlines=True doesn't seem to set the
text encoding correctly. Even if I set only encoding='utf-8', the test
fails. The combination here works for me, \o/.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

gobject/tests/gobject-query.py

@@ -69,7 +69,8 @@ class TestGobjectQuery(unittest.TestCase):
             stdout=subprocess.PIPE,
             stderr=subprocess.PIPE,
             env=env,
-            universal_newlines=True,
+            text=True,
+            encoding='utf-8',
         )
         info.check_returncode()
         out = info.stdout.strip()