ci: publish ci regression list into slack

.github/workflows/wpt.yml

@@ -153,3 +153,34 @@ jobs:
 
       - name: format and send json result
         run: /perf-fmt wpt ${{ github.sha }} wpt.json
+
+  wptdiff:
+    name: perf-fmt
+    needs: perf-fmt
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          repository: 'lightpanda-io/demo'
+          fetch-depth: 0
+
+      - run: |
+          cd ./wptdiff
+          CGO_ENABLED=0 go build
+
+      - run: |
+         ./wptdiff/wptdiff |tee diff.log
+
+      - name: Send regression to slack
+        uses: slackapi/slack-github-action@v3.0.1
+        with:
+          errors: true
+          method: files.uploadV2
+          token: ${{ secrets.CI_SLACK_BOT_TOKEN }}
+          payload: |
+            channel_id: ${{ vars.WPT_SLACK_CHANNEL_ID }}
+            initial_comment: "Last WPT regressions"
+            file: "./diff.log"
+            filename: "wpt-regression-${{ github.sha }}.txt"