Add python update script which parses latest version from atom feed and calls `update-source-version`.
Additionally set meta.changelog url.
Tested with `nix-shell maintainers/scripts/update.nix --argstr package lunatask`.
`appimageTools.wrapType2` no longer creates a binary `$out/bin/${name}` if `pname` and `version` is provided.
Derivations that have worked around this behavior with a `mv $out/bin/{${name},${pname}}` broke as a result.
This should fix most instances.
contex: #271071