ci: remove DCT delegation key last

Author: buchdag

.github/workflows/build-publish-signed.yml

@@ -29,7 +29,6 @@ jobs:
           echo "$DCT_KEY_BASE64" | base64 -d > delegation.key
           chmod 600 delegation.key
           docker trust key load delegation.key --name gha
-          rm delegation.key
 
       - name: Login to DockerHub
         uses: docker/login-action@v3
@@ -49,3 +48,6 @@ jobs:
       - name: Verify the image signature
         run: |
           docker trust inspect --pretty ${{ env.IMAGE_NAME }}:${{ env.IMAGE_TAG }}
+
+      - name: Remove DCT delegation key
+        run: rm delegation.key