fix: support Node >=10

This is a follow-up to testing-library#459.

Author: NMinhNguyen

package.json

@@ -20,7 +20,7 @@
   "author": "Kent C. Dodds <[email protected]> (https://kentcdodds.com)",
   "license": "MIT",
   "engines": {
-    "node": ">=10.18"
+    "node": ">=10"
   },
   "scripts": {
     "build": "kcd-scripts build --ignore \"**/__tests__/**,**/__node_tests__/**,**/__mocks__/**\" && kcd-scripts build --bundle --no-clean",