Fix GithubReleasesUpdateInformation::buildUrl()

[bastimeyer]

Fixes #252

The release asset matching is currently broken on main, as it compares against the browser_download_url instead of name, which can make the AppImage's update pattern accidentally match the repo name in the download URL instead of just the release asset names, leading to a wrong asset selection when trying to update. I have described the issue in detail in #252.

This incorrect matching in the URL is only possible because of the added asterisk char * at the beginning of the pattern a few lines above my changes, here:

AppImageUpdate/src/updateinformation/GithubReleasesZsyncUpdateInformation.cpp

Lines 49 to 50 in 673af3c

	// not ideal, but allows for returning a match for the entire line
	auto pattern = "*" + filename;

I was not sure if you'd want to keep this for compatibility reasons, so I didn't change it.

The AppImage spec however explicitly mentions the file name for matching, not the download URL, so maybe this should be removed, considering the spec's pattern example.

In regards to the sorting at the bottom that is based on the browser_download_url value, that should be fine, as it's the same sorting result after only adding the entries with a matching name to the matchingUrls.

I have validated these changes and the current version from main on a temporary test repo (with a renamed repo while using the main version, for proving the issue).

[TheAssassin]

Good catch, thanks. I don't know what the motivation was back then. (Maybe this was at a time when this other key did not exist...?)