update dependencies

example/pubspec.lock

@@ -7,7 +7,7 @@ packages:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.2.0"
+    version: "2.1.0"
   boolean_selector:
     dependency: transitive
     description:
@@ -94,7 +94,7 @@ packages:
       name: quiver
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.3"
+    version: "2.0.2"
   sky_engine:
     dependency: transitive
     description: flutter
@@ -141,7 +141,7 @@ packages:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.5"
+    version: "0.2.4"
   typed_data:
     dependency: transitive
     description:

pubspec.yaml

@@ -5,7 +5,7 @@ author: Taner Sener <tanersener@gmail.com>
 homepage: https://github.com/tanersener/flutter-ffmpeg
 
 environment:
-  sdk: ">=2.0.0-dev.68.0 <3.0.0"
+  sdk: ">=2.1.0 <3.0.0"
 
 dependencies:
   flutter: