fix: use GitHub API directly instead of gh CLI

The gh CLI is not installed on the runners. Use curl and the GitHub API
directly to set PR labels.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

.github/workflows/detect-pr-pipeline.yaml

@@ -68,6 +68,15 @@ jobs:
 
       - name: Set PR label
         if: github.event_name == 'pull_request'
+        env:
+          GH_TOKEN: ${{ github.token }}
+          REPO: ${{ github.repository }}
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+          PIPELINE_TYPE: ${{ steps.detect.outputs.pipeline-type }}
         run: |
-          gh pr edit "${{ github.event.pull_request.number }}" \
-            --add-label "${{ steps.detect.outputs.pipeline-type }}"
+          curl -sf \
+            -X POST \
+            -H "Authorization: Bearer ${GH_TOKEN}" \
+            -H "Accept: application/vnd.github.v3+json" \
+            "https://api.github.com/repos/${REPO}/issues/${PR_NUMBER}/labels" \
+            -d "{\"labels\":[\"${PIPELINE_TYPE}\"]}"