Set workflow Java version back to 8

.github/workflows/build.yml

@@ -13,10 +13,10 @@ jobs:
       - uses: actions/checkout@v2
         with:
           fetch-depth: 0  # Shallow clones should be disabled for a better relevancy of analysis
-      - name: Set up JDK 11
+      - name: Set up JDK 8
         uses: actions/setup-java@v2
         with:
-          java-version: '11'
+          java-version: '8'
           distribution: 'adopt-hotspot'
       - name: Cache Maven packages
         uses: actions/cache@v1