chore(deps): upgrade to Gatsby v4 (#549)

BREAKING CHANGE: requires gatsby@^4.0.1
BREAKING CHANGE: drops support for Node.js < 14.15

Author: robinmetral

examples/gatsby-starter-source-s3/package.json

@@ -6,16 +6,16 @@
   "license": "MIT",
   "author": "Robin Métral <robin@metral.ch>",
   "dependencies": {
-    "gatsby": "^3.14.3",
-    "gatsby-plugin-image": "^1.14.0",
-    "gatsby-plugin-sharp": "^3.14.2",
-    "gatsby-transformer-sharp": "^3.14.0",
+    "gatsby": "^4.2.0",
+    "gatsby-plugin-image": "^2.2.0",
+    "gatsby-plugin-sharp": "^4.2.0",
+    "gatsby-transformer-sharp": "^4.2.0",
     "react": "^17.0.2",
     "react-dom": "^17.0.2"
   },
   "scripts": {
     "develop": "gatsby develop",
-    "build": "gatsby build",
+    "build": "gatsby build --verbose",
     "serve": "gatsby serve"
   }
 }