build: Install git too

This must be a regression from the timestamp change:
91ed63c

Without this we fail to parse the timestamp and get errors;
maybe something else changed.

Of course, we should use a non-Makefile language for
this so we get proper error checking.  I may move some
of the makefile bits into xtask.rs or so.

Signed-off-by: Colin Walters <walters@verbum.org>

hack/build.sh

@@ -10,3 +10,5 @@ t=$(mktemp --suffix .spec)
 curl -L -o ${t} https://src.fedoraproject.org/rpms/bootc/raw/rawhide/f/bootc.spec
 dnf -y builddep "${t}"
 rm -f "${t}"
+# Extra dependencies
+dnf -y install git