Fix overflow for `PSNR` metric when used with `uint8` input #9697

Job	Run time
check-code / mypy	2m 18s
check-md-links / markdown-link-check	4m 36s
check-package / init-store	5s
check-schema / schema	14s
check-package / pkg-build (ubuntu-latest)	22s
check-package / pkg-check (ubuntu-22.04, 3.8)	2m 37s
check-package / pkg-check (ubuntu-22.04, 3.11)	2m 55s
check-package / pkg-check (macos-12, 3.8)	1m 37s
check-package / pkg-check (macos-12, 3.11)	1m 24s
check-package / pkg-check (windows-2022, 3.8)	3m 28s
check-package / pkg-check (windows-2022, 3.11)	2m 52s
check-package / pkg-guardian	1s
	22m 29s

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