Add permission-check before slack notify

.github/workflows/ci.yml

@@ -310,9 +310,17 @@ jobs:
     needs: [ build_linux, build_macos, build_windows, docs_check ]
     runs-on: ubuntu-20.04
     steps:
+    - name: Check user permission
+        id: check
+        uses: scherermichael-oss/action-has-permission@1.0.6
+        with:
+          required-permission: write
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
     - name: Slack Notification
       uses: lazy-actions/slatify@v3.0.0
-      if: always() && ( github.event_name != 'pull_request' || github.event.pull_request.head.repo.fork == false)
+      if: always() && steps.check.outputs.has-permission && ( github.event_name != 'pull_request' || github.event.pull_request.head.repo.fork == false)
       with:
         type: ${{ job.status }}
         job_name: '*Freqtrade CI*'