fix typo

`matrix.name` doesn't exist.

.github/workflows/wasm.yml

@@ -124,7 +124,7 @@ jobs:
 
       - uses: ./.github/actions/slack
         with:
-          label: ${{ matrix.name }}
+          label: ${{ matrix.entry.name }}
           SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
         if: ${{ failure() && github.event_name == 'push' }}