update gatsby

Author: mylamour

package.json

@@ -7,7 +7,7 @@
     "url": "https://github.com/jazibsawar/gatsby-blog-cosmicjs/issues"
   },
   "dependencies": {
-    "gatsby": "^2.20.4",
+    "gatsby": "^5.0.0",
     "gatsby-background-image": "^0.9.14",
     "gatsby-image": "^2.2.40",
     "gatsby-plugin-google-analytics": "^2.1.35",