Composer: update to YoastCS 3.4.3

PHP_CodeSniffer has released a security fix.

This updates enforces the use of a PHPCS version which include the fixes.

Refs:
* https://github.com/Yoast/yoastcs/releases/tag/3.4.3

Author: jrfnl

composer.json

@@ -19,7 +19,7 @@
 		"ext-zip": "*"
 	},
 	"require-dev": {
-		"yoast/yoastcs": "^3.4.2"
+		"yoast/yoastcs": "^3.4.3"
 	},
 	"minimum-stability": "alpha",
 	"prefer-stable": true,