Update mediawiki/mediawiki-codesniffer requirement from 49.0.0 to 50.0.0 (#558)

Updates the requirements on [mediawiki/mediawiki-codesniffer](https://github.com/wikimedia/mediawiki-tools-codesniffer) to permit the latest version.
- [Changelog](https://github.com/wikimedia/mediawiki-tools-codesniffer/blob/master/HISTORY.md)
- [Commits](wikimedia/mediawiki-tools-codesniffer@v49.0.0...v50.0.0)

---
updated-dependencies:
- dependency-name: mediawiki/mediawiki-codesniffer
  dependency-version: 50.0.0
  dependency-type: direct:development
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

composer.json

@@ -8,7 +8,7 @@
 		"composer/installers": ">=1.0.1"
 	},
 	"require-dev": {
-		"mediawiki/mediawiki-codesniffer": "49.0.0",
+		"mediawiki/mediawiki-codesniffer": "50.0.0",
 		"mediawiki/mediawiki-phan-config": "0.19.0",
 		"mediawiki/minus-x": "2.0.1",
 		"php-parallel-lint/php-console-highlighter": "1.0.0",