Fix matching of lazygit-edit URLs without line numbers (#5311)

### PR Description

Tweak regexp such that a trailing ":" is not included in the file path
extracted from a lazygit-edit URL.

Previously, when matching a URL containing the ":" separator but no line
number, such as `lazygit-edit:///path/to/file.ext:`, the trailing
separator would be included in the matched file path, so lazygit would
open the non-existent file `/path/to/file.ext:`. Notably, such urls are
created when using delta with the hyperlink feature, as suggested in
https://github.com/jesseduffield/lazygit/blob/master/docs/Custom_Pagers.md#delta,
and clicking a file path rather than a line number.

Fixes #5308

pkg/gui/gui.go

@@ -377,7 +377,7 @@ func (gui *Gui) onNewRepo(startArgs appTypes.StartArgs, contextKey types.Context
 
 	gui.g.SetOpenHyperlinkFunc(func(url string, viewname string) error {
 		if strings.HasPrefix(url, "lazygit-edit:") {
-			re := regexp.MustCompile(`^lazygit-edit://(.+?)(?::(\d+))?$`)
+			re := regexp.MustCompile(`^lazygit-edit://(.+?)(?::(\d*))?$`)
 			matches := re.FindStringSubmatch(url)
 			if matches == nil {
 				return fmt.Errorf(gui.Tr.InvalidLazygitEditURL, url)