Bump @ember/string from 3.1.1 to 4.0.0

Bumps [@ember/string](https://github.com/emberjs/ember-string) from 3.1.1 to 4.0.0.
- [Release notes](https://github.com/emberjs/ember-string/releases)
- [Changelog](https://github.com/emberjs/ember-string/blob/master/CHANGELOG.md)
- [Commits](https://github.com/emberjs/ember-string/commits)

---
updated-dependencies:
- dependency-name: "@ember/string"
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

package.json

@@ -111,7 +111,7 @@
     "@ember-data/serializer": "^5.3.9",
     "@ember-data/store": "^5.3.9",
     "@ember/optional-features": "^2.2.0",
-    "@ember/string": "^3.1.1",
+    "@ember/string": "^4.0.0",
     "@ember/test-helpers": "^3.3.1",
     "@embroider/test-setup": "^3.0.3",
     "@fullhuman/postcss-purgecss": "^4.1.3",