Bump ember-cli from 3.3.0 to 3.15.1

Bumps [ember-cli](https://github.com/ember-cli/ember-cli) from 3.3.0 to 3.15.1.
- [Release notes](https://github.com/ember-cli/ember-cli/releases)
- [Changelog](https://github.com/ember-cli/ember-cli/blob/v3.15.1/CHANGELOG.md)
- [Commits](ember-cli/ember-cli@v3.3.0...v3.15.1)

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

Author: dependabot-preview[bot]

package.json

@@ -46,7 +46,7 @@
     "broccoli-test-helper": "^2.0.0",
     "chai": "^4.1.2",
     "co": "^4.6.0",
-    "ember-cli": "~3.3.0",
+    "ember-cli": "~3.15.1",
     "ember-cli-babel": "^7.1.0",
     "ember-cli-blueprint-test-helpers": "^0.19.1",
     "ember-cli-dependency-checker": "^3.0.0",