Bump org.flywaydb:flyway-mysql from 11.20.3 to 12.0.0 in /server

Bumps org.flywaydb:flyway-mysql from 11.20.3 to 12.0.0.

---
updated-dependencies:
- dependency-name: org.flywaydb:flyway-mysql
  dependency-version: 12.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

server/pom.xml

@@ -137,7 +137,7 @@
         <dependency>
             <groupId>org.flywaydb</groupId>
             <artifactId>flyway-mysql</artifactId>
-            <version>11.20.3</version>
+            <version>12.0.0</version>
         </dependency>
         <dependency>
             <groupId>org.mariadb.jdbc</groupId>