internal/rosa/git: shallow clone

The .git directory is destroyed anyway, so no point fetching more than the bare minimum.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/git.go

@@ -105,7 +105,9 @@ func (t Toolchain) NewViaGit(
 git \
 	-c advice.detachedHead=false \
 	clone \
+	--depth=1 \
 	--revision=`+rev+` \
+	--shallow-submodules \
 	--recurse-submodules \
 	`+url+` \
 	/work