Most themes don't work on NixOS

[jzw2]

Many of the themes don't work, since in the up file, they use #!/bin/bash, which isn't available on NixOS. It would work if it was switched to #!/usr/bin/env bash

[VuiMuich]

Good point! Unfortunately it looks like that's up to each theme maintainer to fix, as we can't push directly to all the submodules.

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tagging leftwm/leftwm-theme#33

[ghost]

Isn't it possible to make a CI/CD step to "adapt to nixos" and just replace the shebang?

(Tho I suspect if some paths are different in NixOS a breakage is surely unavoidable).