fix: make esbuild a peer dependency (#62)

BREAKING CHANGE: esbuild is now a peer dependency and needs to be installed separately

Author: Arcath

README.md

@@ -165,6 +165,20 @@ It has more features, fewer bugs, and no runtime!
 
 </details>
 
+<details>
+  <summary>
+    <strong>
+      "Why is esbuild a peer dependancy?"
+    </strong>
+  </summary>
+
+esbuild provides a service written in GO that it interacts with. Only one
+instance of this service can run at a time and it must have an identical version
+to the npm package. If it was a hard dependency you would only be able to use
+the esbuild version mdx-bundler uses.
+
+</details>
+
 ## Table of Contents
 
 <!-- START doctoc generated TOC please keep comment here to allow auto update -->

package.json

@@ -43,26 +43,29 @@
     "@babel/runtime": "^7.14.6",
     "@esbuild-plugins/node-resolve": "^0.1.4",
     "@fal-works/esbuild-plugin-global-externals": "^2.1.1",
-    "esbuild": "^0.12.11",
     "gray-matter": "^4.0.3",
     "remark-frontmatter": "^3.0.0",
     "remark-mdx-frontmatter": "^1.0.1",
     "xdm": "^1.11.1"
   },
+  "peerDependencies": {
+    "esbuild": "0.11.x || 0.12.x"
+  },
   "devDependencies": {
     "@testing-library/react": "^12.0.0",
     "@types/jsdom": "^16.2.12",
-    "@types/react": "^17.0.11",
+    "@types/react": "^17.0.13",
     "@types/react-dom": "^17.0.8",
     "cross-env": "^7.0.3",
+    "esbuild": "^0.12.15",
     "jsdom": "^16.6.0",
     "kcd-scripts": "^11.1.0",
     "left-pad": "^1.3.0",
     "mdx-test-data": "^1.0.1",
     "react": "^17.0.2",
     "react-dom": "^17.0.2",
     "remark-mdx-images": "^1.0.2",
-    "typescript": "^4.3.4",
+    "typescript": "^4.3.5",
     "uvu": "^0.5.1"
   },
   "eslintConfig": {