SCRIPTS: use /usr/bin/env bash instead of /bin/bash for scripts

Given that some OSes have bash in /usr/local/bin and in order not to
give too easy an excuse to Olivier for not backporting fixes, let's
make a few scripts rely on /usr/bin/env bash instead of /bin/bash :-)
diff --git a/scripts/publish-release b/scripts/publish-release
index 6a615a6..5a9a5ce 100755
--- a/scripts/publish-release
+++ b/scripts/publish-release
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # puts the public files online after a release
 # Copyright (c) 2006-2016 Willy Tarreau <w@1wt.eu>
 #