fix(deps): pin dependencies

pubspec.yaml

@@ -19,13 +19,13 @@ environment:
 dependencies:
   flutter:
     sdk: flutter
-  fluro: ^1.4.0
-  package_info: ^0.4.0+3
-  intl: ^0.15.8
+  fluro: 1.6.1
+  package_info: 0.4.0
+  intl: 0.15.8
   url_launcher:
-  http: ^0.12.0+2
+  http: 0.12.0
   photo_view: ^0.3.0 # Newest version is 0.4.0, but it is not complicable with the SDK version.
-  firebase_core: ^0.4.0+6
+  firebase_core: 0.4.4
 #  firebase_auth: ^0.11.1+6
   cloud_firestore: ^0.12.5+2
   firebase_messaging: ^5.0.4
@@ -38,7 +38,7 @@ dependencies:
 dev_dependencies:
   flutter_test:
     sdk: flutter
-  image_test_utils: ^1.0.0
+  image_test_utils: 1.0.0
 
 # For information on the generic Dart part of this file, see the
 # following page: https://www.dartlang.org/tools/pub/pubspec