chore(package): update eslint-config-prettier to version 6.4.0

Closes #28

Author: greenkeeper[bot]

package.json

@@ -28,7 +28,7 @@
     "ava": "2.2.0",
     "eslint": "6.1.0",
     "eslint-config-es2015": "1.1.0",
-    "eslint-config-prettier": "6.0.0",
+    "eslint-config-prettier": "6.4.0",
     "esm": "3.2.25",
     "microbundle": "0.11.0",
     "prettier": "1.18.2",