Bump phpunit/phpunit from 9.6.17 to 9.6.18 #3986

Job	Run time
Debug	1s
Check files / Changed	11s
XML Syntax	0s
Composer / Validation	9s
Code-QL / Analyze (javascript)	1m 44s
PHP CS / Default	4m 3s
PHP CS / Ecg	2m 7s
PHP CS Fixer / Validation	2m 35s
PHPStan / Analyze (ubuntu-latest, 7.4)	4m 8s
PHP CS / PhpCompatibility	5m 49s
PHPStan / Analyze (ubuntu-latest, 8.3)	2m 21s
Unit Tests (Sonar)	0s
PHP Syntax	0s
Unit Tests (OpenMage)	0s
	23m 8s

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