Update .travis.yml

Author: fischerscode

.travis.yml

@@ -11,7 +11,7 @@ install:
 
 script:
   - (cd packages/dart && pub get)
-  - (cd packages/dart && dart run build_runner build)
+  - (cd packages/dart && dart run build_runner build --delete-conflicting-outputs)
   - (cd packages/dart && pub run test)
   - (cd packages/flutter && flutter pub get)
   - (cd packages/flutter && flutter test --no-pub test/)