unbreak typo in sync-search-elasticsearch.yml (#32833)

.github/workflows/sync-search-elasticsearch.yml

@@ -131,7 +131,7 @@ jobs:
         env:
           FASTLY_TOKEN: ${{ secrets.FASTLY_TOKEN }}
           FASTLY_SERVICE_ID: ${{ secrets.FASTLY_SERVICE_ID }}
-          FASTLY_SURROGATE_KEY: api-search:${{ matrix-language }}
+          FASTLY_SURROGATE_KEY: api-search:${{ matrix.language }}
         run: .github/actions-scripts/purge-fastly-edge-cache.js
 
       - name: Send Slack notification if workflow fails