feat: use #!/usr/bin/env bash in all scripts

[FireSquid6]

Is your feature request related to a problem? Please describe.

#!/usr/bin/env bash is more portable than what is currently used, #!/bin/bash. This means that nix users have to spend 3 seconds being annoyed whenever they create a new project.

Describe the solution you'd like to see

Exactly what I have implemented in my fork. Just changing the shebangs.

Describe alternate solutions

nix users could simply cope.

Additional information

I'll make the PR and whatnot if this feature is approved.