cmd: Fix type and name of mgf1 argument #961

Job	Run time
build on fedora:39	1m 55s
build on ubuntu:24.04	1m 43s
build on fedora:40	1m 43s
build on ubuntu:23.10	1m 34s
Build dist with Linux	47s
build on ubuntu:22.04	1m 43s
build on ubuntu:20.04	1m 54s
build on debian:12	1m 41s
build on debian:11	1m 45s
Build Windows release (windows-latest, x86)	8m 30s
Build MacOS release (macos-latest, amd)	57s
Build Windows release (windows-latest, x64)	8m 50s
Build MacOS release (macos-latest-xlarge, arm)	48s
	33m 50s

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