⬆️ Bump ember-template-lint from 2.21.0 to 4.0.0 (#517)

Bumps [ember-template-lint](https://github.com/ember-template-lint/ember-template-lint) from 2.21.0 to 4.0.0.
- [Release notes](https://github.com/ember-template-lint/ember-template-lint/releases)
- [Changelog](https://github.com/ember-template-lint/ember-template-lint/blob/master/CHANGELOG.md)
- [Commits](ember-template-lint/ember-template-lint@v2.21.0...v4.0.0)

---
updated-dependencies:
- dependency-name: ember-template-lint
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

package.json

@@ -88,7 +88,7 @@
     "ember-resolver": "^8.0.2",
     "ember-source": "~3.26.1",
     "ember-source-channel-url": "^3.0.0",
-    "ember-template-lint": "^2.18.1",
+    "ember-template-lint": "^4.0.0",
     "ember-template-lint-plugin-prettier": "^3.0.1",
     "ember-try": "^2.0.0",
     "eslint": "^7.20.0",