Bump @open-wc/testing from 3.2.0 to 4.0.0

Bumps [@open-wc/testing](https://github.com/open-wc/open-wc/tree/HEAD/packages/testing) from 3.2.0 to 4.0.0.
- [Release notes](https://github.com/open-wc/open-wc/releases)
- [Changelog](https://github.com/open-wc/open-wc/blob/master/packages/testing/CHANGELOG.md)
- [Commits](https://github.com/open-wc/open-wc/commits/@open-wc/[email protected]/packages/testing)

---
updated-dependencies:
- dependency-name: "@open-wc/testing"
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

package.json

@@ -29,7 +29,7 @@
   "homepage": "https://github.com/koddsson/web-dev#readme",
   "devDependencies": {
     "@github/prettier-config": "^0.0.6",
-    "@open-wc/testing": "^3.2.0",
+    "@open-wc/testing": "^4.0.0",
     "@web/dev-server": "^0.3.7",
     "@web/dev-server-esbuild": "^1.0.1",
     "@web/rollup-plugin-html": "^2.1.2",