Fix GitHub Actions

.github/workflows/gradle.yml

@@ -11,10 +11,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2
-    - name: Set up JDK 8
+    - name: Set up JDK 17
       uses: actions/setup-java@v2
       with:
-        java-version: '8'
+        java-version: '17'
         distribution: 'adopt'
     - name: Grant execute permission for gradlew
       run: chmod +x gradlew