remove github actions

.github/workflows/dart.yml

@@ -1,22 +0,0 @@
-name: build
-
-on:
-  push:
-    branches: [master]
-  pull_request:
-    branches: [master]
-
-jobs:
-  test:
-    runs-on: ubuntu-latest
-
-    steps:
-      - uses: actions/checkout@v1
-      - uses: actions/setup-java@v1
-        with:
-          java-version: "12.x"
-      - uses: subosito/flutter-action@v1
-        with:
-          channel: dev
-      - run: flutter pub get
-      - run: flutter test