CI: Use Jdk 21

Author: daniel-raffler

.github/workflows/ci.yml

@@ -54,7 +54,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        java-version: [24]
+        java-version: [21]
         arch: [arm64]
     runs-on: ${{ matrix.arch == 'arm64' && 'macos-latest' || 'macos-15-intel' }}
     steps: