fix(deps): pin dependency yaml to v2.8.1

Author: clavery

packages/b2c-dx-mcp/package.json

@@ -96,7 +96,7 @@
     "@modelcontextprotocol/sdk": "1.26.0",
     "@oclif/core": "4.8.0",
     "@salesforce/b2c-tooling-sdk": "workspace:*",
-    "yaml": "^2.8.1",
+    "yaml": "2.8.1",
     "zod": "3.25.76"
   },
   "devDependencies": {