use specific Bash shebang on CI package install script

This script does not use any Bashisms as far as I can tell, but we rely on Bash
elsewhere for shell scripts so may as well standardize on this here.

diff --git a/ci/install-packages.sh b/ci/install-packages.sh
index fb943c96dafdd0c169b7d45f88697adaf04613ac..2658b565d3c63d2df813f24a191227a19c74e526 100755 (executable)
--- a/ci/install-packages.sh
+++ b/ci/install-packages.sh
@@ -1,5 +1,6 @@
-#!/bin/sh -e
+#!/usr/bin/env bash
 
+set -e
 set -x
 
 if [ "$( uname -s )" = "Darwin" ]; then