remove github workflow

.github/workflows/build.yml

@@ -1,32 +0,0 @@
-name: Client Build
-on:
-  push:
-    branches: [ master ]
-  pull_request:
-    branches: [ master ]
-jobs:
-  build-ios:
-    name: Build iOS app
-    runs-on: macos-latest
-    steps:
-      - uses: actions/checkout@v1
-      - uses: subosito/flutter-action@v1
-        with:
-          flutter-version: '1.17.3'
-          channel: 'stable'
-      - run: flutter pub get
-      - run: flutter build ios --no-codesign
-  build-android:
-    name: Build Android app
-    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:
-          flutter-version: '1.17.3'
-          channel: 'stable'
-      - run: flutter pub get
-      - run: flutter build apk