fix: upgrade gatsby from 2.23.3 to 2.23.4

Snyk has created this PR to upgrade gatsby from 2.23.3 to 2.23.4.

See this package in NPM:
https://www.npmjs.com/package/gatsby

See this project in Snyk:
https://app.snyk.io/org/creyd-github-marketplace/project/7687a902-5880-4dba-8e64-1ed2c0311711?utm_source=github&utm_medium=upgrade-pr

package.json

@@ -16,7 +16,7 @@
   },
   "dependencies": {
     "dateformat": "^3.0.3",
-    "gatsby": "^2.23.3",
+    "gatsby": "^2.23.4",
     "gatsby-plugin-manifest": "^2.4.11",
     "react": "^16.13.1",
     "react-dom": "^16.13.1",