fix(promote): simplify release file fallback using /dev/null

Replace the prepare-release-file step with an inline /dev/null fallback
to satisfy svenstaro/upload-release-action's required file input when no
file is provided.

Author: jobcespedes

.github/workflows/promote.yml

@@ -315,26 +315,13 @@ jobs:
           git-user-email: ${{ inputs.git-user-email }}
           git-add-files: ${{ steps.resolve_changelog_git_add_files.outputs.files || inputs.git-add-files }}
 
-      - name: prepare release file
-        if: inputs.update-release-enabled && inputs.push-git
-        id: prepare_release_file
-        shell: bash
-        run: |
-          set -euo pipefail
-          FILE="${{ inputs.update-release-file }}"
-          if [ -z "$FILE" ]; then
-            touch /tmp/.release-placeholder
-            FILE="/tmp/.release-placeholder"
-          fi
-          echo "file=$FILE" >> "$GITHUB_OUTPUT"
-
       - name: publish github release
         if: inputs.update-release-enabled && inputs.push-git
         uses: svenstaro/upload-release-action@v2
         with:
           repo_token: ${{ inputs.update-release-token || github.token }}
           tag: ${{ inputs.update-release-tag || format('{0}{1}', inputs.version-tag-prefix, steps.release_version.outputs.version) }}
-          file: ${{ steps.prepare_release_file.outputs.file }}
+          file: ${{ inputs.update-release-file || '/dev/null' }}
           file_glob: true
           body: ${{ steps.release_changelog.outputs.content }}
           overwrite: ${{ inputs.update-release-overwrite }}