chore(deps): update actions/upload-artifact action to v4 (#58)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/build-example.yml

@@ -48,7 +48,7 @@ jobs:
         run: flutter build apk --no-shrink
 
       - name: Upload APK
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         if: ${{ matrix.channel == 'stable' }}
         with:
           name: app