feat: update DOM Testing Library to latest

BREAKING CHANGE: This updates @testing-library/dom, please check the changelog for the most recent version of that package to know whether you are impacted by these changes.

Author: kentcdodds

package.json

@@ -42,7 +42,7 @@
   "license": "MIT",
   "dependencies": {
     "@babel/runtime": "^7.8.4",
-    "@testing-library/dom": "^6.15.0",
+    "@testing-library/dom": "beta",
     "@types/testing-library__cypress": "^5.0.3"
   },
   "devDependencies": {