Update Psalm to v6, Mark shipped classes as soft `@final` #347

Job	Run time
ci / Generate job matrix	10s
ci / QA Checks (PHPUnit [8.3, latest], ubuntu-latest, laminas/laminas-continuous-integration-action@v1...	20s
ci / QA Checks (PHPUnit [8.2, lowest], ubuntu-latest, laminas/laminas-continuous-integration-action@v1...	23s
ci / QA Checks (PHPUnit [8.1, locked], ubuntu-latest, laminas/laminas-continuous-integration-action@v1...	18s
ci / QA Checks (PHPUnit [8.3, lowest], ubuntu-latest, laminas/laminas-continuous-integration-action@v1...	22s
ci / QA Checks (PHPUnit [8.4, lowest], ubuntu-latest, laminas/laminas-continuous-integration-action@v1...	20s
ci / QA Checks (PHPUnit [8.4, latest], ubuntu-latest, laminas/laminas-continuous-integration-action@v1...	19s
ci / QA Checks (PHPUnit [8.2, latest], ubuntu-latest, laminas/laminas-continuous-integration-action@v1...	22s
ci / QA Checks (Backward Compatibility Check [@default, locked], ubuntu-latest, laminas/laminas-contin...	18s
ci / QA Checks (PHPUnit [8.1, lowest], ubuntu-latest, laminas/laminas-continuous-integration-action@v1...	20s
ci / QA Checks (Psalm [8.1, locked], ubuntu-latest, laminas/laminas-continuous-integration-action@v1, ...	19s
ci / QA Checks (PHPUnit [8.1, latest], ubuntu-latest, laminas/laminas-continuous-integration-action@v1...	20s
ci / QA Checks (PHPCodeSniffer [8.1, locked], ubuntu-latest, laminas/laminas-continuous-integration-ac...	18s
	4m 9s

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