version.sh: don't suppress error messages from git availability check

otherwise there is no feedback at all.
as it happens, this also fixes a bashism

Signed-off-by: Sergei Trofimovich <slyfox@inbox.ru>

maint/version.sh

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-git --version &>/dev/null || exit
+git --version >/dev/null || exit
 
 curr_dir=$(pwd)