Fix path of upload_url file used in release workflow

Author: benfrancis

.github/workflows/release.yml

@@ -72,7 +72,7 @@ jobs:
  - name: Display structure of downloaded files
  run: ls -R
  - name: Set upload_url
- run: echo "UPLOAD_URL=$(cat upload_url/upload_url)" >> $GITHUB_ENV
+ run: echo "UPLOAD_URL=$(cat upload_url)" >> $GITHUB_ENV
  - name: Set release version
  run: echo "RELEASE_VERSION=${GITHUB_REF:10}" >> $GITHUB_ENV
  - uses: actions/checkout@v2