chore: use /usr/bin/env to locate the bash interpreter based on the u…

…ser's PATH settings. (red-hat-data-services#1197)

On MacOSX, /bin/bash is quite outdate 3.2.57 and does not suport
`declare -A` which leads to the get_all_manifests.sh to fail.

Signed-off-by: Luca Burgazzoli <lburgazzoli@gmail.com>

get_all_manifests.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 set -e
 
 GITHUB_URL="https://github.com"