fix: guess we need 21 instead of 22 as well...

Author: bruberu

.github/actions/build_setup/action.yml

@@ -17,11 +17,11 @@ runs:
         distribution: zulu
         java-version: 8
 
-    - name: Set up JDK 22
+    - name: Set up JDK 21
       uses: actions/setup-java@v5
       with:
         distribution: zulu
-        java-version: 22
+        java-version: 21
 
     - name: Setup Gradle
       uses: gradle/actions/setup-gradle@v5