Add .zon (zig object notation) files to icon.rs

ziglang/zig#14290

This is the official file ending of zon files, at the time of writing this only used to specify dependencies, versions and files of zig packages

src/theme/icon.rs

@@ -731,6 +731,7 @@ impl IconTheme {
             ("yml", "\u{e60b}"),             // ""
             ("zip", "\u{f410}"),             // ""
             ("zig", "\u{e6a9}"),             // ""
+            ("zon", "\u{e60b}"),             // ""
             ("zshrc", "\u{f489}"),           // ""
             ("zsh-theme", "\u{f489}"),       // ""
             ("zsh", "\u{f489}"),             // ""