test ubuntu on beta

Author: tmthecoder

.github/workflows/dargon2_flutter_tests.yml

@@ -80,10 +80,13 @@ jobs:
         include:
           - os: macos-latest
             FLUTTER_DEVICE: macos
+            FLUTTER_CHANNEL: stable
           - os: ubuntu-latest
             FLUTTER_DEVICE: linux
+            FLUTTER_CHANNEL: beta
           - os: windows-latest
             FLUTTER_DEVICE: windows
+            FLUTTER_CHANNEL: stable
     steps:
       - name: Checkout
         uses: actions/checkout@v2
@@ -92,8 +95,9 @@ jobs:
       - name: Download Flutter
         uses: subosito/flutter-action@v2
         with:
-          channel: 'stable'
+          channel: ${{ matrix.FLUTTER_CHANNEL }}
           cache: true
+          cache-key: ${{ matrix.FLUTTER_CHANNEL }}
       - name: Enable Flutter Desktop
         run: |
           flutter config --enable-linux-desktop