Update dart.yml

Author: robert-virkus

.github/workflows/dart.yml

@@ -25,7 +25,7 @@ jobs:
       - uses: dart-lang/setup-dart@9a04e6d73cca37bd455e0608d7e5092f881fd603
 
       - name: Install dependencies
-        run: dart pub get
+        run: flutter pub get
 
       # Uncomment this step to verify the use of 'dart format' on each commit.
       # - name: Verify formatting