Update slevomat/coding-standard requirement from ^6.1.5 to ^6.2.0

Updates the requirements on [slevomat/coding-standard](https://github.com/slevomat/coding-standard) to permit the latest version.
- [Release notes](https://github.com/slevomat/coding-standard/releases)
- [Commits](slevomat/coding-standard@6.1.5...6.2.0)

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

Author: dependabot-preview[bot]

composer.json

@@ -28,7 +28,7 @@
     "require": {
         "php": "^7.2",
         "dealerdirect/phpcodesniffer-composer-installer": "^0.6.2",
-        "slevomat/coding-standard": "^6.1.5",
+        "slevomat/coding-standard": "^6.2.0",
         "squizlabs/php_codesniffer": "^3.5.4"
     },
     "config": {