chore(ci): upgrade upload/download-artifact to Node.js 24-compatible versions

upload-artifact v7, download-artifact v8. Clears last Node.js 20 deprecation warning.

.github/workflows/build.yml

@@ -69,7 +69,7 @@ jobs:
         run: ./gradlew assembleRelease
 
       - name: Upload APK artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: app-release
           path: android/app/build/outputs/apk/release/app-release.apk
@@ -81,7 +81,7 @@ jobs:
     permissions:
       contents: write
     steps:
-      - uses: actions/download-artifact@v4
+      - uses: actions/download-artifact@v8
         with:
           name: app-release