update package

change pub proxy
update flutter sdk v0.7.0

Author: CarGuo

pubspec.lock

@@ -234,7 +234,7 @@ packages:
       name: flutter_svg
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.5.5+1"
+    version: "0.5.4"
   flutter_webview_plugin:
     dependency: "direct main"
     description: