build: Set Gradle version to 7.6 in GitHub Actions

Author: linyimin0812

.github/workflows/build.yml

@@ -13,10 +13,11 @@ jobs:
       - uses: actions/checkout@v2
         with:
           fetch-depth: 0  # Shallow clones should be disabled for a better relevancy of analysis
-      - name: Set up JDK 1.8
+      - name: Set up JDK 11
         uses: actions/setup-java@v1
         with:
-          java-version: 1.8
+          java-version: 11
+          gradle-version: 7.6
       - name: Cache SonarCloud packages
         uses: actions/cache@v1
         with: