ci: fixed the apk upload error (#9)

Author: AxelSilverdew

.github/workflows/nightly-release.yml

@@ -420,7 +420,7 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:
           upload_url: ${{ needs.prepare_release.outputs.upload_url }}
-          asset_path: ${{ steps.sign_apk.outputs.signedReleaseFile }}
+          asset_path: ${{ steps.sign_apk.outputs.signedFile }}
           asset_name: alvr_client_android.apk
           asset_content_type: application/vnd.android.package-archive
       - name: Upload client library