CI: Call benchmarks webhook with curl instead of a dedicated action

The workflow-webhook action that was being used didn't work on macOS or
machines without Docker, so let's create the payload ourselves, sign it
and send it over using plain old `curl`.

.github/workflows/js-benchmarks.yml

@@ -62,7 +62,16 @@ jobs:
           retention-days: 90
 
       - name: 'Call webhook'
-        uses: distributhor/workflow-webhook@v3
-        with:
-          webhook_url: ${{ secrets.JS_BENCHMARKS_WEBHOOK_URL }}
-          webhook_secret: ${{ secrets.JS_BENCHMARKS_WEBHOOK_SECRET }}
+        shell: bash
+        run: |
+          echo -n '{                                                                       \
+              "commit": "${{ github.sha }}",                                               \
+          }' > request.json
+          curl \
+              --fail \
+              --silent \
+              --show-error \
+              --header 'Content-Type: application/json' \
+              --header "X-Hub-Signature-256: sha256=$(openssl dgst -sha256 -hmac '${{ secrets.JS_BENCHMARKS_WEBHOOK_SECRET }}' request.json)" \
+              --data-binary '@request.json' \
+              '${{ secrets.JS_BENCHMARKS_WEBHOOK_URL }}'