Update workflow

.github/workflows/main.yml

@@ -38,6 +38,12 @@ jobs:
         with:
           path: ${{env.EM_CACHE_FOLDER}}
           key: ${{env.EM_VERSION}}-${{ runner.os }}
+      # java 6 is required for using closure compiler
+      - uses: actions/setup-java@v1
+        with:
+          java-version: '6' # The JDK version to make available on the path.
+          java-package: jdk # (jre, jdk, or jdk+fx) - defaults to jdk
+          architecture: x64 # (x64 or x86) - defaults to
       - uses: mymindstorm/setup-emsdk@v6
         with:
           version: ${{env.EM_VERSION}}