Upgrade to Gatsby v3 (#123)

* chore: bump gatsby, TS & React dependencies

* Remove custom schema types

They don’t appear to be working even though themes are allowed to customise schemas.

Reference:
- gatsbyjs/gatsby#26864
- https://github.com/gatsbyjs/gatsby/issues/15544\
- gatsbyjs/gatsby#16928

* Update peer deps for Gatsby

example/package.json

@@ -15,9 +15,9 @@
     "start": "gatsby serve"
   },
   "dependencies": {
-    "gatsby": "^2.28.0",
+    "gatsby": "^3.3.1",
     "gatsby-theme-code-notes": "*",
-    "react": "^16.13.0",
-    "react-dom": "^16.13.0"
+    "react": "^17.0.2",
+    "react-dom": "^17.0.2"
   }
 }

gatsby-theme-code-notes/gatsby-node.js

@@ -203,17 +203,6 @@ exports.createSchemaCustomization = ({ actions }) => {
       openSearch: OpenSearch
       showDate: Boolean
     }
-    type MdxFrontmatter @infer {
-      title: String!
-      tags: [String]
-      emoji: String
-      link: String
-      created: Date
-      modified: Date
-    }
-    type MdxFields @infer {
-      slug: String
-    }
   `
   createTypes(typeDefs)
 }

gatsby-theme-code-notes/package.json

@@ -29,7 +29,7 @@
     "mdx"
   ],
   "peerDependencies": {
-    "gatsby": "^2.28.0",
+    "gatsby": "^2.28.0 || ^3.0.0",
     "react": "^16.13.0 || ^17.0.0",
     "react-dom": "^16.13.0 || ^17.0.0"
   },
@@ -47,22 +47,22 @@
     "@theme-ui/prism": "0.4.0-rc.5",
     "color-hash": "^1.0.3",
     "copee": "^1.0.6",
-    "gatsby-core-utils": "^1.3.23",
-    "gatsby-plugin-catch-links": "^3.2.0",
-    "gatsby-plugin-local-search": "^2.0.0",
-    "gatsby-plugin-mdx": "^1.2.46",
+    "gatsby-core-utils": "^2.3.0",
+    "gatsby-plugin-catch-links": "^3.3.0",
+    "gatsby-plugin-local-search": "^2.0.1",
+    "gatsby-plugin-mdx": "^2.3.0",
     "gatsby-plugin-meta-redirect": "^1.1.1",
     "gatsby-plugin-og-image": "^0.0.1",
-    "gatsby-plugin-react-helmet": "^3.3.13",
+    "gatsby-plugin-react-helmet": "^4.3.0",
     "gatsby-plugin-redirects": "^1.0.0",
-    "gatsby-plugin-sharp": "^2.6.39",
-    "gatsby-plugin-theme-ui": "0.4.0-rc.5",
-    "gatsby-plugin-typescript": "^2.4.21",
+    "gatsby-plugin-sharp": "^3.3.1",
+    "gatsby-plugin-theme-ui": "0.7.3",
+    "gatsby-plugin-typescript": "^3.3.0",
     "gatsby-remark-double-brackets-link": "^0.1.8",
-    "gatsby-remark-images": "^3.3.33",
-    "gatsby-source-filesystem": "^2.3.34",
+    "gatsby-remark-images": "^5.0.0",
+    "gatsby-source-filesystem": "^3.3.0",
     "gatsby-transformer-markdown-references": "^0.1.5",
-    "gatsby-transformer-sharp": "^2.5.17",
+    "gatsby-transformer-sharp": "^3.3.0",
     "lodash": "^4.17.20",
     "mkdirp": "^1.0.3",
     "querystring": "^0.2.0",
@@ -78,7 +78,7 @@
     "remark-unwrap-images": "^2.0.0",
     "text-cleaner": "^1.2.1",
     "theme-ui": "0.4.0-rc.5",
-    "typescript": "^4.1.2"
+    "typescript": "^4.2.4"
   },
   "devDependencies": {
     "@types/node": "^14.14.10",
@@ -87,12 +87,12 @@
     "@types/react-helmet": "^6.1.0",
     "dotenv-cli": "^4.0.0",
     "eslint-plugin-react-hooks": "^4.2.0",
-    "gatsby": "^2.28.0",
+    "gatsby": "^3.3.1",
     "husky": "^4.3.0",
     "lint-staged": "^10.5.3",
     "prettier": "^2.2.1",
-    "react": "^16.13.0",
-    "react-dom": "^16.13.0",
+    "react": "^17.0.2",
+    "react-dom": "^17.0.2",
     "release-it": "^14.2.2"
   }
 }