Upgrade actions/upload-artifact to v4

Author: grote

.github/workflows/build.yml

@@ -45,7 +45,7 @@ jobs:
         run: ./gradlew compileDebugAndroidTestSources check assemble ktlintCheck
 
       - name: Upload APKs
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: seedvault-${{ github.sha }}-apks
           path: |