Bump eslint-config-prettier from 6.5.0 to 6.9.0

Bumps [eslint-config-prettier](https://github.com/prettier/eslint-config-prettier) from 6.5.0 to 6.9.0.
- [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@v6.5.0...v6.9.0)

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

package.json

@@ -39,7 +39,7 @@
     "coveralls": "3.0.7",
     "eslint": "6.6.0",
     "eslint-config-airbnb-base": "14.0.0",
-    "eslint-config-prettier": "6.5.0",
+    "eslint-config-prettier": "6.9.0",
     "eslint-plugin-import": "2.18.2",
     "eslint-plugin-mocha": "6.2.1",
     "mocha": "6.2.2",