fix-infrastructure-objects: Don't assume /bin/bash to be present

Unlike /bin/sh, /bin/bash is not mandated by POSIX and is not
present on some platforms (e.g., NixOS). Use the bash in the
user's PATH.

fix-infrastructure-objects

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 set -e