Update alleyinteractive/alley-coding-standards requirement

Updates the requirements on [alleyinteractive/alley-coding-standards](https://github.com/alleyinteractive/alley-coding-standards) to permit the latest version.
- [Release notes](https://github.com/alleyinteractive/alley-coding-standards/releases)
- [Changelog](https://github.com/alleyinteractive/alley-coding-standards/blob/develop/CHANGELOG.md)
- [Commits](alleyinteractive/alley-coding-standards@v1.0.0...v2.1.0)

---
updated-dependencies:
- dependency-name: alleyinteractive/alley-coding-standards
  dependency-type: direct:development
...

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

composer.json

@@ -22,7 +22,7 @@
         "mantle-framework/support": "^0.12"
     },
     "require-dev": {
-        "alleyinteractive/alley-coding-standards": "^1.0",
+        "alleyinteractive/alley-coding-standards": "^2.1",
         "mantle-framework/testkit": "^0.12",
         "nunomaduro/collision": "^5.0"
     },