Update slim/slim requirement from ^4.11 to ^4.12

Updates the requirements on [slim/slim](https://github.com/slimphp/Slim) to permit the latest version.
- [Release notes](https://github.com/slimphp/Slim/releases)
- [Changelog](https://github.com/slimphp/Slim/blob/4.x/CHANGELOG.md)
- [Commits](slimphp/Slim@4.11.0...4.12.0)

---
updated-dependencies:
- dependency-name: slim/slim
  dependency-type: direct:production
...

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

composer.json

@@ -20,7 +20,7 @@
     "require": {
         "php": "^7.4 || ^8.0",
         "psr/http-message": "^1.1",
-        "slim/slim": "^4.11",
+        "slim/slim": "^4.12",
         "twig/twig": "^3.6",
         "symfony/polyfill-php81": "^1.27"
     },