build: use env to find bash path

Type: make
Change-Id: I9f87134ac05d99051888024f889f05dae8e3feec
Signed-off-by: Damjan Marion <damarion@cisco.com>

src/scripts/version

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 # Copyright (c) 2015 Cisco and/or its affiliates.
 # Licensed under the Apache License, Version 2.0 (the "License");