Bumped Flutter version in CI

Author: sveinbjornt

.github/workflows/tests.yml

@@ -22,10 +22,10 @@ jobs:
           distribution: 'zulu'
           java-version: '12.x'
       - name: Setup Flutter SDK
-        uses: flutter-actions/setup-flutter@v3
+        uses: flutter-actions/setup-flutter@v4
         with:
           channel: stable
-          version: 3.22.0
+          version: 3.29.1
       - name: Install dependencies
         run: |
           flutter config --no-analytics