fix: upgrade lodash from 4.17.15 to 4.17.20

Snyk has created this PR to upgrade lodash from 4.17.15 to 4.17.20.

See this package in npm:
https://www.npmjs.com/package/lodash

See this project in Snyk:
https://app.snyk.io/org/github-newrelic/project/f888c3c2-125f-4ff7-a0c6-0181b3c27c8b?utm_source=github&utm_medium=upgrade-pr

Author: snyk-bot

package-lock.json

@@ -27,7 +27,7 @@
     "gatsby-transformer-json": "^2.4.3",
     "js-cookie": "^2.2.1",
     "js-search": "^2.0.0",
-    "lodash": "^4.17.15",
+    "lodash": "^4.17.20",
     "marked": "^1.1.1",
     "node-sass": "^4.14.1",
     "prism-react-renderer": "^1.1.1",