deps: bump io.quarkus:quarkus-bom from 3.11.2 to 3.12.0

Bumps [io.quarkus:quarkus-bom](https://github.com/quarkusio/quarkus) from 3.11.2 to 3.12.0.
- [Release notes](https://github.com/quarkusio/quarkus/releases)
- [Commits](quarkusio/quarkus@3.11.2...3.12.0)

---
updated-dependencies:
- dependency-name: io.quarkus:quarkus-bom
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

java/school-timetabling/build.gradle

@@ -3,7 +3,7 @@ plugins {
     id "io.quarkus" version "3.11.2"
 }
 
-def quarkusVersion = "3.11.2"
+def quarkusVersion = "3.12.0"
 def timefoldVersion = "999-SNAPSHOT"
 def profile = System.properties['profile'] ?: ''
 def enterprise = System.properties['enterprise'] ?: ''