Try java 8

Author: liufengyun

.github/workflows/ci.yaml

@@ -58,8 +58,8 @@ jobs:
     container: lampepfl/dotty:2020-04-24
 
     steps:
-      - name: Set JDK 11 as default
-        run: echo "::add-path::/usr/lib/jvm/java-11-openjdk-amd64/bin"
+      # - name: Set JDK 11 as default
+      #   run: echo "::add-path::/usr/lib/jvm/java-11-openjdk-amd64/bin"
 
       - name: Checkout cleanup script
         uses: actions/checkout@v2