ci: serialize release creation so the upload matrix never races #95

Job	Run time
build	26s
create-release	9s
upload-assets (ubuntu-latest, linux, arm64, subenum, subenum-linux-arm64)	30s
upload-assets (macos-latest, darwin, arm64, subenum, subenum-macos-arm64)	31s
upload-assets (ubuntu-latest, linux, amd64, subenum, subenum-linux-amd64)	20s
upload-assets (ubuntu-latest, darwin, amd64, subenum, subenum-macos-amd64)	25s
upload-assets (windows-latest, windows, amd64, subenum.exe, subenum-windows-amd64.exe)	1m 0s
	3m 21s

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