remove override on package_resolver (#201)

diff --git a/pubspec.yaml b/pubspec.yaml
index 887059e..547ad18 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -14,6 +14,3 @@
 
 dev_dependencies:
   test: ^1.3.0
-
-dependency_overrides:
-  package_resolver: 1.0.4