composer(deps-dev): bump infection/infection from 0.13.6 to 0.15.3

Bumps [infection/infection](https://github.com/infection/infection) from 0.13.6 to 0.15.3.
- [Release notes](https://github.com/infection/infection/releases)
- [Changelog](https://github.com/infection/infection/blob/master/CHANGELOG.md)
- [Commits](infection/infection@0.13.6...0.15.3)

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

composer.json

@@ -20,7 +20,7 @@
     "ergebnis/license": "^1.0.0",
     "ergebnis/phpstan-rules": "~0.15.2",
     "ergebnis/test-util": "^1.1.0",
-    "infection/infection": "~0.13.6",
+    "infection/infection": "~0.15.3",
     "jangregor/phpstan-prophecy": "~0.8.0",
     "phpstan/extension-installer": "^1.0.4",
     "phpstan/phpstan": "~0.12.40",