Use limit in mysql tests as it won't work without it

Author: mcraveiro

tests/mysql/test_offset.cpp

@@ -42,7 +42,7 @@ TEST(mysql, test_offset) {
   sqlgen::write(conn, people1).value();
 
   const auto query =
-      sqlgen::read<std::vector<Person>> | order_by("id"_c) | offset(3);
+      sqlgen::read<std::vector<Person>> | order_by("id"_c) | limit(-1) | offset(3);
 
   const auto people2 = query(conn).value();