[libgdx] Upgrade to JDK 17 for GH builds

.github/workflows/spine-libgdx.yml

@@ -10,12 +10,12 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
-    - name: Set up JDK 1.8
+    - uses: actions/checkout@v2
+    - name: Set up JDK 17
       uses: actions/setup-java@v3
       with:
-        distribution: 'zulu'
-        java-version: "8"
+        java-version: '17'
+        distribution: 'temurin'
 
     - name: Cache Gradle packages
       uses: actions/cache@v3