Remove zsync

[DeinAlptraum]

I didn't see zsync actually being used anywhere, so attempt to build without it.

See #931

[DeinAlptraum]

Built without a problem and runs just fine on my end.
@s09bQ5 since you were the last one to touch this, do you know if/why we include zsync?

[s09bQ5]

Built without a problem and runs just fine on my end. @s09bQ5 since you were the last one to touch this, do you know if/why we include zsync?

We include it because of

2024-12-31T14:11:06.1259383Z appimagetool, continuous build (commit 8bbf694), build <local dev build> built on 2024-12-31 14:02:19 UTC
2024-12-31T14:11:06.1262064Z WARNING: zsyncmake command is missing, please install it if you want to use binary delta updates

But it's just a warning and we don't do binary delta updates.

[barbeque-squared]

I had a quick look at the appimagetool repo, doesn't appear to be any way to suppress the warning. It looks to be called from a Makefile, it might be useful to have an echo right before that command that any warning about binary delta updates can be ignored because we don't use them? Has the bonus of touching the Makefile in this PR too.

[DeinAlptraum]

might be useful to have an echo right before that command

Added this