Use custom actions

Author: liufengyun

Diff for: .github/workflows/ci.yaml

@@ -101,15 +101,25 @@ jobs:
     runs-on: [self-hosted, Windows]
 
     steps:
+      - name: Git Checkout
+        uses: actions/checkout@v2
+
       - name: Test
-        run: sbt ";compile ;test"
+        uses: liufengyun/actions@v1
+        with:
+          command: sbt ";compile ;test"
 
   test_bootstrapped-windows:
     runs-on: [self-hosted, Windows]
 
     steps:
+      - name: Git Checkout
+        uses: actions/checkout@v2
+
       - name: Test
-        run: sbt ";dotty-bootstrapped/compile ;dotty-bootstrapped/test;sjsJUnitTests/test"
+        uses: liufengyun/actions@v1
+        with:
+          command: sbt ";dotty-bootstrapped/compile ;dotty-bootstrapped/test;sjsJUnitTests/test"
 
   community_build:
     runs-on: [self-hosted, Linux]