Update phpcodesniffer plugin config

- Adds file extensions to be checked. - Removes the WordPress-Core ruleset which is included in WordPress-Extra.

Author: IanDelMar

.codeclimate.yml

@@ -13,7 +13,8 @@ plugins:
  phpcodesniffer:
  enabled: true
  config:
- standard: "WordPress-Core,WordPress-Docs,WordPress-Extra"
+ file_extensions: "php"
+ standard: "WordPress-Docs,WordPress-Extra"
  phpmd:
  enabled: true
  checks: