FIX: tracking_system update in BIDSPath class

Author: JuliusWelzel

mne_bids/path.py

@@ -422,6 +422,7 @@ def __init__(
             space=space,
             split=split,
             description=description,
+            tracking_system=tracking_system,
             root=root,
             datatype=datatype,
             suffix=suffix,
@@ -443,6 +444,7 @@ def entities(self):
             "recording": self.recording,
             "split": self.split,
             "description": self.description,
+            "tracking_system": self.tracking_system,
         }
 
     @property
@@ -576,6 +578,15 @@ def description(self) -> str | None:
     def description(self, value):
         self.update(description=value)
 
+    @property
+    def tracking_system(self) -> str | None:
+        """The tracking system entity."""
+        return self._tracking_system
+
+    @tracking_system.setter
+    def tracking_system(self, value):
+        self.update(tracking_system=value)
+
     @property
     def suffix(self) -> str | None:
         """The filename suffix."""