fix(shebang): use more general shebang #!/usr/bin/env bash

[sotte]

/bin/bash does not exist on all systems. /usr/bin/env bash is more general.

Motivation and Context

/bin/bash is not supported by all systems.

How Has This Been Tested?

I ran it :)

Breaking Changes

None.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

[obra]

Closing as duplicate of #700, which covers the same change (#!/bin/bash → #!/usr/bin/env bash in all 13 shell scripts). #700 was first by 3 days and has been merged to dev. Thanks for the contribution!