Fix old sqlite

Author: erikjohnston

synapse/storage/background_updates.py

@@ -1105,7 +1105,7 @@ def run_validate_constraint_and_delete_rows_schema_delta(
         # PRIMARY KEY), and so don't need to be recreated.
         txn.execute(
             """
-            SELECT sql FROM sqlite_schema
+            SELECT sql FROM sqlite_master
             WHERE tbl_name = ? AND type != 'table' AND sql IS NOT NULL
             """,
             (table,),

tests/storage/test_background_update.py

@@ -526,7 +526,7 @@ def delta(txn: LoggingTransaction) -> None:
             # Ensure the index exists in the schema.
             self.get_success(
                 self.store.db_pool.simple_select_one_onecol(
-                    table="sqlite_schema",
+                    table="sqlite_master",
                     keyvalues={"tbl_name": "test_constraint"},
                     retcol="name",
                 )