Update phpstan/phpstan-phpunit requirement from ^1.3 to ^1.4 #283

Job	Run time
Coding Standards	16s
Unit Tests (PHP 8.2) on ubuntu-latest	14s
Unit Tests (PHP 8.2) on ubuntu-latest	17s
Static Analysis	17s
Unit Tests (PHP 8.2) on macos-latest	1m 8s
Unit Tests (PHP 8.2) on macos-latest	55s
Unit Tests (PHP 8.2) on windows-latest	56s
Unit Tests (PHP 8.2) on windows-latest	50s
Unit Tests (PHP 8.3) on ubuntu-latest	12s
Unit Tests (PHP 8.3) on ubuntu-latest	14s
Unit Tests (PHP 8.3) on macos-latest	1m 11s
Unit Tests (PHP 8.3) on macos-latest	1m 12s
Unit Tests (PHP 8.3) on windows-latest	45s
Unit Tests (PHP 8.3) on windows-latest	1m 3s
	9m 30s

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