test: add pg_catalog as an expected schema (#821)

Adds `pg_catalog` as an expected schema to the JDBC metadata tests.

Fixes #810

Author: olavloite

src/test/java/com/google/cloud/spanner/jdbc/it/ITJdbcPgDatabaseMetaDataTest.java

@@ -752,6 +752,10 @@ public void testGetSchemas() throws SQLException {
         assertEquals(getDefaultCatalog(database), rs.getString("TABLE_CATALOG"));
         assertEquals("information_schema", rs.getString("TABLE_SCHEM"));
 
+        assertTrue(rs.next());
+        assertEquals(getDefaultCatalog(database), rs.getString("TABLE_CATALOG"));
+        assertEquals("pg_catalog", rs.getString("TABLE_SCHEM"));
+
         assertTrue(rs.next());
         assertEquals(getDefaultCatalog(database), rs.getString("TABLE_CATALOG"));
         assertEquals("public", rs.getString("TABLE_SCHEM"));