Set javaVersion property in pipeline to avoid warnings on Java 17

Author: themkat

.github/workflows/build.yml

@@ -22,4 +22,4 @@ jobs:
           java-version: ${{ matrix.java }}
       - uses: gradle/gradle-build-action@v2
       - name: Build
-        run: ./gradlew :server:build :shared:build
+        run: ./gradlew :server:build :shared:build -PjavaVersion=${{ matrix.java }}