fix: packages/contentstack-export/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-LODASH-15869625
- https://snyk.io/vuln/SNYK-JS-LODASH-15869619

Author: snyk-bot

packages/contentstack-export/package.json

@@ -13,7 +13,7 @@
     "big-json": "^3.2.0",
     "bluebird": "^3.7.2",
     "chalk": "^4.1.2",
-    "lodash": "^4.17.23",
+    "lodash": "^4.18.1",
     "merge": "^2.1.1",
     "mkdirp": "^1.0.4",
     "progress-stream": "^2.0.0",