Make @types/react-dom a regular dependency

`@types/react-dom` is used in `types/index.d.ts`, which is an external interface, and thus needs to be declared as a regular rather than a dev dependency so that it is picked up by users of `@testing-library/react`.

Author: fmeum

package.json

@@ -45,11 +45,11 @@
   "license": "MIT",
   "dependencies": {
     "@babel/runtime": "^7.12.5",
-    "@testing-library/dom": "^8.0.0"
+    "@testing-library/dom": "^8.0.0",
+    "@types/react-dom": "^17.0.0"
   },
   "devDependencies": {
     "@testing-library/jest-dom": "^5.11.6",
-    "@types/react-dom": "^17.0.0",
     "dotenv-cli": "^4.0.0",
     "kcd-scripts": "^11.1.0",
     "npm-run-all": "^4.1.5",