zig fmt: additionally format .zon files

Author: alichraghi

src/main.zig

@@ -4523,7 +4523,7 @@ fn fmtPathDir(
 
         if (is_dir and (mem.eql(u8, entry.name, "zig-cache") or mem.eql(u8, entry.name, "zig-out"))) continue;
 
-        if (is_dir or entry.kind == .File and mem.endsWith(u8, entry.name, ".zig")) {
+        if (is_dir or entry.kind == .File and (mem.endsWith(u8, entry.name, ".zig") or mem.endsWith(u8, entry.name, ".zon"))) {
             const full_path = try fs.path.join(fmt.gpa, &[_][]const u8{ file_path, entry.name });
             defer fmt.gpa.free(full_path);