Update slevomat/coding-standard requirement from ^6.3 to ^7.0

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@6.3.0...7.0.8)

---
updated-dependencies:
- dependency-name: slevomat/coding-standard
  dependency-type: direct:development
...

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

Author: dependabot[bot]

composer.json

@@ -29,7 +29,7 @@
       "phpunit/phpunit": "^9.3",
       "phpmd/phpmd": "^2.6",
       "squizlabs/php_codesniffer": "^3.3",
-      "slevomat/coding-standard": "^6.3"
+      "slevomat/coding-standard": "^7.0"
     },
     "autoload": {
         "psr-4": {