global: use '/usr/bin/env bash' instead of '/usr/bin/bash' in shebangs

Using the method from @cemeyer
(https://github.com/espressif/esp-idf/pull/3166):

find . -name \*.sh -exec sed -i "" -e 's|^#!.*bin/bash|#!/usr/bin/env bash|' {} +

Closes https://github.com/espressif/esp-idf/pull/3166.

tools/ci/push_to_github.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 # gitlab-ci script to push current tested revision (tag or branch) to github