feat: add returning to mysql

mysql/delete_statement_test.go

@@ -24,3 +24,11 @@ ORDER BY table1.col1
 LIMIT ?;
 `, int64(1), int64(1))
 }
+
+func TestDeleteWithWhereAndReturning(t *testing.T) {
+	assertStatementSql(t, table1.DELETE().WHERE(table1Col1.EQ(Int(1))).RETURNING(table1Col1), `
+DELETE FROM db.table1
+WHERE table1.col1 = ?
+RETURNING table1.col1 AS "table1.col1";
+`, int64(1))
+}