chore(deps): bump @testing-library/user-event from 12.8.3 to 13.1.8

Bumps [@testing-library/user-event](https://github.com/testing-library/user-event) from 12.8.3 to 13.1.8.
- [Release notes](https://github.com/testing-library/user-event/releases)
- [Changelog](https://github.com/testing-library/user-event/blob/master/CHANGELOG.md)
- [Commits](https://github.com/testing-library/user-event/compare/v12.8.3...v13.1.8)

Signed-off-by: dependabot[bot] <support@github.com>

plugins/techdocs/package.json

@@ -56,7 +56,7 @@
     "@backstage/test-utils": "^0.1.10",
     "@testing-library/jest-dom": "^5.10.1",
     "@testing-library/react": "^11.2.5",
-    "@testing-library/user-event": "^12.0.7",
+    "@testing-library/user-event": "^13.1.8",
     "@types/react": "^16.9",
     "@types/jest": "^26.0.7",
     "@types/node": "^14.14.32",