Fix SQL migration script URL

[skip ci]

Author: noplanman

CHANGELOG.md

@@ -227,7 +227,7 @@ Exclamation symbols (:exclamation:) note something of importance e.g. breaking c
 ### Deprecated
 - Move `hideKeyboard` to `removeKeyboard`.
 
-[0.55.0-sql-migration]: https://github.com/php-telegram-bot/core/tree/master/utils/db-schema-update/0.54.0-unreleased.sql
+[0.55.0-sql-migration]: https://github.com/php-telegram-bot/core/tree/master/utils/db-schema-update/0.54.1-0.55.0.sql
 [0.55.0-bc-move-animation-out-of-games-namespace]: https://github.com/php-telegram-bot/core/wiki/Breaking-backwards-compatibility#move-animation-out-of-games-namespace
 [0.54.0-sql-migration]: https://github.com/php-telegram-bot/core/tree/master/utils/db-schema-update/0.53.0-0.54.0.sql
 [0.54.0-bc-rename-constants]: https://github.com/php-telegram-bot/core/wiki/Breaking-backwards-compatibility#rename-constants