add jujutsu to ignored files

[jujutsu](https://github.com/martinvonz/jj) is an alternative to git

src/project_manager.zig

@@ -769,6 +769,7 @@ fn walk_tree_async(a_: std.mem.Allocator, root_path_: []const u8) (SpawnError ||
 
 const filtered_dirs = [_][]const u8{
     ".git",
+    ".jj",
     ".cache",
     ".var",
     "zig-out",