chore(deps-dev): bump eslint-config-prettier from 6.9.0 to 6.15.0

Bumps [eslint-config-prettier](https://github.com/prettier/eslint-config-prettier) from 6.9.0 to 6.15.0.
- [Release notes](https://github.com/prettier/eslint-config-prettier/releases)
- [Changelog](https://github.com/prettier/eslint-config-prettier/blob/master/CHANGELOG.md)
- [Commits](prettier/eslint-config-prettier@v6.9.0...v6.15.0)

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

Author: dependabot-preview[bot]

package-lock.json

@@ -56,7 +56,7 @@
     "eslint": "6.8.0",
     "eslint-config-airbnb": "17.1.1",
     "eslint-config-airbnb-base": "13.2.0",
-    "eslint-config-prettier": "6.9.0",
+    "eslint-config-prettier": "6.15.0",
     "eslint-plugin-import": "2.20.2",
     "gavel-spec": "5.0.0",
     "husky": "3.1.0",