test(datatype, system-tables): enable test for pg_proc

Author: Brooke-white

test/integration/datatype/test_system_table_queries.py

@@ -28,7 +28,7 @@
     "pg_namespace",
     "pg_opclass",
     "pg_operator",
-    # "pg_proc",  # has unsupported type oid 30
+    "pg_proc",
     "pg_rewrite",
     "pg_shdepend",
     "pg_statistic",