Use bash binary from env instead of /bin/bash for scripts

It's not possible to run any of the scripts on distributions which do
have `bash` not in `/bin`. This is being fixed by using `/usr/bin/env
bash` instead.

Signed-off-by: Sascha Grunert <sgrunert@suse.com>

hack/tree_status.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 set -e
 
 SUGGESTION="${SUGGESTION:-sync the vendor.conf and commit all changes.}"