Fix minimum MSI threshold for infection tool

Signed-off-by: Marijn van Wezel <96489967+marijnvanwezel@users.noreply.github.com>

Author: marijnvanwezel

.github/CONTRIBUTING.md

@@ -69,7 +69,7 @@ After making your changes and adding your tests, you can check whether the minim
 ```
 $ XDEBUG_MODE=coverage php vendor/bin/phpunit --testsuite unit
 $ php vendor/bin/coverage-check coverage/clover.xml 90
-$ XDEBUG_MODE=coverage php vendor/bin/infection --min-msi=8
+$ XDEBUG_MODE=coverage php vendor/bin/infection --min-msi=85
 ```
 
 ## Running test suites