Restricted tests to Postgres (only supported database with custom type names) and fixed minor diff issue (comma)

Author: NicholasLYang

diesel_cli/tests/print_schema.rs

@@ -70,6 +70,7 @@ fn print_schema_column_renaming() {
 }
 
 #[test]
+#[cfg(feature = "postgres")]
 fn print_schema_type_renaming() {
     test_print_schema("print_schema_type_renaming", vec!["--with-docs"]);
 }

diesel_cli/tests/print_schema/print_schema_type_renaming/postgres/expected.rs

@@ -14,6 +14,6 @@ table! {
         /// Its SQL type is `UserJob`.
         ///
         /// (Automatically generated by Diesel.)
-        job -> UserJob
+        job -> UserJob,
     }
 }