Update webhook closed PR message link to clau.de

Replace the Google Forms link with the new plugin directory
submission link (https://clau.de/plugin-directory-submission).

https://claude.ai/code/session_01NxRDJKDvFR2d4wC4ppDEDT

.claude-plugin/marketplace.json

@@ -684,17 +684,6 @@
         "url": "https://github.com/semgrep/mcp-marketplace.git"
       },
       "homepage": "https://github.com/semgrep/mcp-marketplace.git"
-    },
-    {
-      "name": "data",
-      "description": "Data engineering for Apache Airflow and Astronomer. Author DAGs with best practices, debug pipeline failures, trace data lineage, profile tables, migrate Airflow 2 to 3, and manage local and cloud deployments.",
-      "category": "development",
-      "source": {
-        "source": "url",
-        "url": "https://github.com/astronomer/agents.git",
-        "sha": "7ef022b02f5296b5ecc52ba0db3ba9345ec03c9e"
-      },
-      "homepage": "https://github.com/astronomer/agents"
     }
   ]
 }