test: improve coverage of curie validation

Issue linkml/linkml#1701 has discovered an erroneous validation of CURIE
prefixes, since apparently it doesn't accept characters '_' and '.'.

This patch extends the tests to provide test coverage for the expected
values to work, avoiding future regressions.

Signed-off-by: Silvano Cirujano Cuesta <silvano.cirujano-cuesta@siemens.com>

Author: Silvanoc

tests/test_utils/test_metamodelcore.py

@@ -64,6 +64,8 @@ def test_curie(self):
         self.assertFalse(Curie.is_valid("type"))
         self.assertEqual(":type", Curie(":type"))
         self.assertTrue(Curie.is_valid(':type'))
+        self.assertTrue(Curie.is_valid('WIKIDATA_PROPERTY:P854'))
+        self.assertTrue(Curie.is_valid('WIKIDATA.PROPERTY:P854'))
         with self.assertRaises(ValueError):
             Curie("1df:type")
         self.assertFalse(Curie.is_valid('1df:type'))