chore(deps-dev): Bump squizlabs/php_codesniffer from 3.5.5 to 3.5.6

Bumps [squizlabs/php_codesniffer](https://github.com/squizlabs/PHP_CodeSniffer) from 3.5.5 to 3.5.6.
- [Release notes](https://github.com/squizlabs/PHP_CodeSniffer/releases)
- [Commits](squizlabs/PHP_CodeSniffer@3.5.5...3.5.6)

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

composer.json

@@ -41,7 +41,7 @@
     "roots/wp-password-bcrypt": "1.0.0"
   },
   "require-dev": {
-    "squizlabs/php_codesniffer": "^3.5.4",
+    "squizlabs/php_codesniffer": "^3.5.6",
     "roave/security-advisories": "dev-master"
   },
   "config": {