Update mediawiki/mediawiki-codesniffer requirement from 37.0.0 to 38.0.0

Updates the requirements on [mediawiki/mediawiki-codesniffer](https://github.com/wikimedia/mediawiki-tools-codesniffer) to permit the latest version.
- [Release notes](https://github.com/wikimedia/mediawiki-tools-codesniffer/releases)
- [Changelog](https://github.com/wikimedia/mediawiki-tools-codesniffer/blob/master/HISTORY.md)
- [Commits](wikimedia/mediawiki-tools-codesniffer@v37.0.0...v38.0.0)

---
updated-dependencies:
- dependency-name: mediawiki/mediawiki-codesniffer
  dependency-type: direct:development
...

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

composer.json

@@ -39,7 +39,7 @@
 	},
 	"require-dev": {
 		"php": ">=7.4.3",
-		"mediawiki/mediawiki-codesniffer": "37.0.0",
+		"mediawiki/mediawiki-codesniffer": "38.0.0",
 		"mediawiki/mediawiki-phan-config": "0.11.0"
 	},
 	"extra": {