GitHub Actions: use protobuf-compiler for Java

.github/workflows/java.yml

@@ -8,13 +8,10 @@ jobs:
 
     steps:
       - uses: actions/checkout@v2
+      - run: sudo apt-get install protobuf-compiler
       - name: Set up JDK 1.8
         uses: actions/setup-java@v1
         with:
           java-version: 1.8
-      - name: Install Protoc
-        uses: arduino/setup-protoc@v1
-        with:
-          version: '3.x'
       - name: Build with Maven
         run: mvn -B package --file pom.xml