Update dependency infection/infection to ^0.26.21

| datasource | package             | from    | to      |
| ---------- | ------------------- | ------- | ------- |
| packagist  | infection/infection | 0.26.19 | 0.26.21 |

Author: renovate[bot]

composer.json

@@ -20,7 +20,7 @@
     },
     "require-dev": {
         "phpunit/phpunit": "^9.6.7",
-        "infection/infection": "^0.26.19"
+        "infection/infection": "^0.26.21"
     },
     "autoload": {
         "psr-4": {