Update minimum MySQL version

see WoltLab/WCF@b1e5c20

Author: TimWolla

docs/migration/wsc55/php.md

@@ -5,7 +5,7 @@
 The minimum requirements have been increased to the following:
 
 - **PHP:** 8.1.2 (64 bit only); `intl` extension
-- **MySQL:** 8.0.29
+- **MySQL:** 8.0.30
 - **MariaDB:** 10.5.12
 
 It is recommended to make use of the newly introduced features whereever possible.