Add an xsd to `phpcs` config #43

Job	Run time
Generate job matrix	10s
QA Checks (PHPUnit [8.0, locked], ubuntu-latest, laminas/laminas-continuous-integration-action@v1...	22s
QA Checks (PHPUnit [8.0, lowest], ubuntu-latest, laminas/laminas-continuous-integration-action@v1...	20s
QA Checks (PHPUnit [8.0, latest], ubuntu-latest, laminas/laminas-continuous-integration-action@v1...	21s
QA Checks (PHPUnit [8.1, lowest], ubuntu-latest, laminas/laminas-continuous-integration-action@v1...	29s
QA Checks (PHPUnit [8.1, latest], ubuntu-latest, laminas/laminas-continuous-integration-action@v1...	28s
QA Checks (PHPUnit [8.2, lowest], ubuntu-latest, laminas/laminas-continuous-integration-action@v1...	22s
QA Checks (PHPUnit [8.2, latest], ubuntu-latest, laminas/laminas-continuous-integration-action@v1...	21s
QA Checks (PHPCodeSniffer [8.0, locked], ubuntu-latest, laminas/laminas-continuous-integration-ac...	21s
	3m 14s

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