define sdkmanrc and reference it in github action

.github/workflows/package.yaml

@@ -15,11 +15,10 @@ jobs:
       - uses: actions/checkout@v6
         with:
           submodules: recursive
-      - name: Set up JDK 25.0.2
-        uses: actions/setup-java@v5
+      - name: Set up SDKman and Java
+        uses: actions/sdkman-action@v1
         with:
-          distribution: 'temurin'
-          java-version: '25.0.2'
+          sdkmanrc: .sdkmanrc
       - name: Show Build Versions
         run: ./gradlew -v
       - name: Build with Gradle

.sdkmanrc

@@ -0,0 +1,3 @@
+# Enable auto-env through the sdkman_auto_env config
+# Add key=value pairs of SDKs to use below
+java=25.0.2-tem