clarify types of optional fields

Author: penguinland

src/tracker/track.py

@@ -1,3 +1,5 @@
+from typing import Optional
+
 import numpy as np
 import torch
 from viam.services.vision import Detection
@@ -31,11 +33,11 @@ def __init__(
 
         self.label = label
 
-        self.label_from_reid = None
+        self.label_from_reid: Optional[str] = None
         self.conf_from_reid = 0
 
-        self.label_from_faceid = None
-        self.conf_from_faceid = None
+        self.label_from_faceid: Optional[str] = None
+        self.conf_from_faceid: Optional[str]  = None
 
         self.persistence: int = 0
         self.is_candidate: bool = is_candidate