chore(deps-dev): bump wp-coding-standards/wpcs from 2.3.0 to 3.1.0

Bumps [wp-coding-standards/wpcs](https://github.com/WordPress/WordPress-Coding-Standards) from 2.3.0 to 3.1.0.
- [Release notes](https://github.com/WordPress/WordPress-Coding-Standards/releases)
- [Changelog](https://github.com/WordPress/WordPress-Coding-Standards/blob/develop/CHANGELOG.md)
- [Commits](WordPress/WordPress-Coding-Standards@2.3.0...3.1.0)

---
updated-dependencies:
- dependency-name: wp-coding-standards/wpcs
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

composer.json

@@ -50,7 +50,7 @@
     "installer-disable": true
   },
   "require-dev": {
-    "wp-coding-standards/wpcs": "2.3.0",
+    "wp-coding-standards/wpcs": "3.1.0",
     "dealerdirect/phpcodesniffer-composer-installer": "^0.7.1",
     "phpunit/phpunit": "5.*",
     "yoast/phpunit-polyfills": "^1.0"