Use fvm for building workflows (#694)

Author: SchrodingersGat

.github/workflows/android.yaml

@@ -50,5 +50,7 @@ jobs:
 
     - name: Build for Android
       run: |
-        flutter pub get
-        flutter build apk --debug
+        dart pub global activate fvm
+        fvm install
+        fvm flutter pub get
+        fvm flutter build apk --debug

.github/workflows/ios.yaml

@@ -46,9 +46,11 @@ jobs:
 
     - name: Build for iOS
       run: |
-        flutter pub get
+        dart pub global activate fvm
+        fvm install
+        fvm flutter pub get
         cd ios
         pod repo update
         pod install
         cd ..
-        flutter build ios --release --no-codesign --no-tree-shake-icons
+        fvm flutter build ios --release --no-codesign --no-tree-shake-icons