chore(action): Update github action

Author: Pyozer

.github/workflows/example_app.yml

@@ -8,7 +8,7 @@ jobs:
       run:
         working-directory: ./example
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: subosito/flutter-action@v2
         with:
           channel: 'stable'

.github/workflows/main.yml

@@ -7,7 +7,7 @@ jobs:
     steps:
       # The branch or tag ref that triggered the workflow will be checked out.
       # https://github.com/actions/checkout
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       # Setup a flutter environment.
       # https://github.com/marketplace/actions/flutter-action
       - uses: subosito/flutter-action@v2