Add stage_paths field to PatchSet struct in tests

- Introduced a new field, `stage_paths`, to the `PatchSet` struct in `patch_compute.rs` to track filesystem paths for staging.
- Updated test cases to initialize `stage_paths` alongside other fields, ensuring consistency in patch set creation.

These changes enhance the testing framework by providing additional context for staged paths in patch sets.

tests/tests/git_sync_defaults.rs

@@ -17,7 +17,7 @@ use std::process::Command;
 use std::time::Duration;
 use std::{fs, thread};
 
-use librojo::web_api::{AddedInstance, InstanceUpdate, WriteRequest};
+use librojo::web_api::{InstanceUpdate, WriteRequest};
 use rbx_dom_weak::types::{Ref, Variant};
 use rbx_dom_weak::{ustr, UstrMap};