Use dart container

Author: tmthecoder

.github/workflows/dart-build.yml

@@ -9,12 +9,10 @@ on:
 jobs:
   test:
     runs-on: ubuntu-latest
-
+    container:
+      image:  google/dart:latest
     steps:
     - uses: actions/checkout@v2
-    - uses: cedx/[email protected]
-      with: 
-        release-channel: beta
     - name: Install dependencies
       run: pub get
     - name: Run tests