fix: packages/catalog-model/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-AJV-15274295

Author: snyk-io[bot]

packages/catalog-model/package.json

@@ -47,7 +47,7 @@
     "@backstage/config": "workspace:^",
     "@backstage/errors": "workspace:^",
     "@backstage/types": "workspace:^",
-    "ajv": "^8.10.0",
+    "ajv": "^8.18.0",
     "json-schema": "^0.4.0",
     "lodash": "^4.17.21",
     "uuid": "^8.0.0"