ci: update nightly release time to UK midnight #786

Job	Run time
ci-data	5s
Push source gem	0s
Compile native gem for x86_64-darwin	6m 57s
Compile native gem for arm64-darwin	6m 53s
Compile native gem for x86_64-linux	11m 9s
Compile native gem for x64-mingw-ucrt	6m 54s
Compile native gem for x86_64-linux-musl	6m 58s
Compile native gem for aarch64-linux	6m 36s
Compile native gem for aarch64-linux-musl	6m 44s
	52m 16s

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