chore: add @types/chai for TypeScript test files

Author: marshallswain

package-lock.json

@@ -65,6 +65,7 @@
     "@elastic/elasticsearch": "^8.19.1",
     "@eslint/js": "^9.34.0",
     "@feathersjs/adapter-tests": "^5.0.34",
+    "@types/chai": "^5.2.3",
     "@types/mocha": "^10.0.0",
     "@types/node": "^18.19.124",
     "@typescript-eslint/eslint-plugin": "^8.42.0",