fix: remove deprecated cleanup-after-each (#598)

BREAKING CHANGE: This removes `@testing-library/react/cleanup-after-each` which is deprecated and hasn't done anything for many versions.

Author: kentcdodds

cleanup-after-each.js

@@ -26,7 +26,6 @@
   },
   "files": [
     "dist",
-    "cleanup-after-each.js",
     "dont-cleanup-after-each.js",
     "pure.js"
   ],
@@ -86,4 +85,4 @@
     "url": "https://github.com/testing-library/react-testing-library/issues"
   },
   "homepage": "https://github.com/testing-library/react-testing-library#readme"
-}
+}