📦️(react) pure ESM package

Previously we had some configuration in package.json that were falsely
indicating that the react package was supporting CJS, which wasn't the
case. So this commit makes it clear that the package is pure ESM.

packages/react/package.json

@@ -8,12 +8,10 @@
   "type": "module",
   "license": "MIT",
   "module": "./dist/index.js",
-  "main": "./dist/index.cjs",
   "types": "./dist/index.d.ts",
   "exports": {
     ".": {
-      "import": "./dist/index.js",
-      "require": "./dist/index.cjs",
+      "default": "./dist/index.js",
       "types": "./dist/index.d.ts"
     },
     "./style": "./dist/style.css",