chore: release 4.0.0 (#1034)

* chore: release 4.0.0

* fix: null check on null value

---------

Co-authored-by: Niraj Nandish <nirajnandish@icloud.com>

Author: Sembauke

mobile-app/lib/ui/views/learn/challenge/challenge_viewmodel.dart

@@ -391,7 +391,7 @@ class ChallengeViewModel extends BaseViewModel {
         description: 'Are you sure you want to reset your code?',
         mainButtonTitle: 'Reset');
 
-    if (res!.confirmed) {
+    if (res?.confirmed == true) {
       Challenge? currChallenge = await challenge;
 
       for (ChallengeFile file in currChallenge!.files) {

mobile-app/pubspec.yaml

@@ -1,7 +1,7 @@
 name: freecodecamp
 description: freecodecamp.org app.
 publish_to: none
-version: 3.5.0+30500
+version: 4.0.0+40000
 environment:
   sdk: ">=2.12.0 <3.0.0"
 dependencies: