fix: Skip namespace separator test when server uses default separator

The test_rest_custom_namespace_separator test expects the REST catalog
to advertise '.' as the namespace separator, which only newer server
versions do. Skip the test when the server uses the default '\x1f'
separator to avoid failures with pinned image versions.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: sumedhsakdeo

tests/integration/test_catalog.py

@@ -614,6 +614,8 @@ def test_rest_custom_namespace_separator(rest_catalog: RestCatalog, table_schema
     Tests that the REST catalog correctly picks up the namespace-separator from the config endpoint.
     The REST Catalog is configured with a '.' namespace separator.
     """
+    if rest_catalog._namespace_separator != ".":
+        pytest.skip("REST catalog server does not advertise '.' namespace separator")
     assert rest_catalog._namespace_separator == "."
 
     unique_id = uuid.uuid4().hex