fix missing entry in pubspec

frontend/pubspec.lock

@@ -1015,4 +1015,4 @@ packages:
     version: "3.1.3"
 sdks:
   dart: ">=3.7.0 <4.0.0"
-  flutter: ">=3.29.1"
+  flutter: ">=3.27.0"

frontend/pubspec.yaml

@@ -20,7 +20,7 @@ version: 1.0.0+1
 
 environment:
   sdk: '>=3.3.4 <4.0.0'
-  flutter: 3.29.1
+  flutter: '3.29.1'
 
 # Dependencies specify other packages that your package needs in order to work.
 # To automatically upgrade your package dependencies to the latest versions