Update dependency infection/infection to ^0.26.20

| datasource | package             | from    | to      |
| ---------- | ------------------- | ------- | ------- |
| packagist  | infection/infection | 0.26.19 | 0.26.20 |

Author: renovate[bot]

composer.json

@@ -10,7 +10,7 @@
     "require-dev": {
         "cache/integration-tests": "dev-master",
         "cache/tag-interop": "dev-master",
-        "infection/infection": "^0.26.19",
+        "infection/infection": "^0.26.20",
         "phpunit/phpunit": "^9.6.7"
     },
     "license": "MIT",