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/setup_python.sh

@@ -1,4 +1,4 @@
-#! /bin/bash
+#!/usr/bin/env bash
 
 # Regexp for matching job names which are incompatible with Python 3
 # - assign_test, nvs_compatible_test, IT - auto_test_script causes the incompatibility