fix: nixos specific no such file or directory

[orhnk]

I was getting no such file or directory errors in NixOS.

It turns out that the shebang was causing this error.

To address this problem, this PR explicitly tells the OS to execute the script using dash

Note

this will make it easier to spot people who did not install dash and complaining about the bar is not working

[MinePro120]

I'd like to propose a different fix for this: change the shebang to #!/usr/bin/env dash and tell me if the issue persists @orhnk.

[MinePro120]

Test #196 please @orhnk.