ci: Add GPU tests on `merge_group` #826

Job	Run time
build	8m 32s
check-lurk-compiles	1m 20s
code-quality / lints	1m 42s
code-quality / msrv	44s
code-quality / wasm-build	40s
licenses-audits / cargo-deny (advisories, licenses, bans, ...)	40s
link-checker / linkChecker	4s
	13m 42s

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