update dart getter

Author: tmthecoder

.github/workflows/dart-build.yml

@@ -12,9 +12,9 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2
-    - uses: dart-lang/setup-dart@v1
+    - uses: cedx/setup-dart@v2.5.0
       with: 
-        sdk: beta
+        release-channel: beta
     - name: Install dependencies
       run: pub get
     - name: Run tests