chore(deps): update dependency @testing-library/dom to v9

Author: renovate[bot]

package-lock.json

@@ -37,7 +37,7 @@
     "@edx/browserslist-config": "^1.1.1",
     "@edx/frontend-build": "^12.4.19",
     "@edx/frontend-platform": "^3.0.1",
-    "@testing-library/dom": "8.20.0",
+    "@testing-library/dom": "9.0.0",
     "@testing-library/jest-dom": "5.16.5",
     "@testing-library/react": "10.4.9",
     "enzyme": "3.11.0",