Not usable on alpine-based based workflow containers

[rmsc]

The shell is hardcoded to 'bash' everywhere, which is causing problems in alpine-based worfklow containers, where only 'sh' is available:

Error: crun: executable file `bash` not found in $PATH: No such file or directory: OCI runtime attempted to invoke a command that was not found

I wonder if setting the shell like this is really needed, or if that could just be removed.
EDIT: it is, it needs to be changed to 'sh' for alpine.

[rmsc]

Unfortunately changing this is not enough for running in alpine-based CI images.

The action uses pip to install python packages, which is not supported in alpine:

Images URIS=
error: externally-managed-environment
× This environment is externally managed
╰─> 
    The system-wide python installation should be maintained using the system
    package manager (apk) only.
    
    If the package in question is not packaged already (and hence installable via
    "apk add py3-somepackage"), please consider installing it inside a virtual
    environment, e.g.:
    
    python3 -m venv /path/to/venv
    . /path/to/venv/bin/activate
    pip install mypackage
    
    To exit the virtual environment, run:
    
    deactivate
    
    The virtual environment is not deleted, and can be re-entered by re-sourcing
    the activate file.
    
    To automatically manage virtual environments, consider using pipx (from the
    pipx package).
note: If you believe this is a mistake, please contact your Python installation or OS distribution provider. You can override this, at the risk of breaking your Python installation or OS, by passing --break-system-packages.
hint: See PEP 668 for the detailed specification.

[rmsc]

BTW I'm trying to use this action in Forgejo, not Github. Instead of using VMs, Forgejo uses podman/docker based runners.

If you feel this is out-of-scope, please feel free to close.