Add Postgresql warning when using DROP INDEX without CONCURRENTLY keyword

django_migration_linter/sql_analyser/postgresql.py

@@ -13,4 +13,11 @@ class PostgresqlAnalyser(BaseAnalyser):
             "mode": "one_liner",
             "type": "warning",
         },
+        {
+            "code": "DROP_INDEX",
+            "fn": lambda sql, **kw: re.search("DROP INDEX", sql) and not re.search("INDEX CONCURRENTLY", sql),
+            "msg": "DROP INDEX locks table",
+            "mode": "one_liner",
+            "type": "warning",
+        },
     ]