Bump squizlabs/php_codesniffer from 2.8.1 to 3.5.3

Bumps [squizlabs/php_codesniffer](https://github.com/squizlabs/PHP_CodeSniffer) from 2.8.1 to 3.5.3.
- [Release notes](https://github.com/squizlabs/PHP_CodeSniffer/releases)
- [Commits](squizlabs/PHP_CodeSniffer@2.8.1...3.5.3)

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

composer.json

@@ -23,7 +23,7 @@
         "satooshi/php-coveralls": "^1.0",
         "symfony/debug": "^3.2",
         "phpmd/phpmd": "@stable",
-        "squizlabs/php_codesniffer": "^2.8",
+        "squizlabs/php_codesniffer": "^3.5",
         "phploc/phploc": "^3.0",
         "sebastian/phpcpd": "^3.0",
         "pdepend/pdepend": "^2.5"