[Bug] Timezone awareness for session start time checks (#471)

* fix timezone awareness for session start time checks

* fix

* Apply suggestions from code review

* Update nwbfile_metadata.py

---------

Co-authored-by: Garrett Michael Flynn <[email protected]>

Author: CodyCBakerPhD

src/nwbinspector/checks/nwbfile_metadata.py

@@ -28,8 +28,11 @@ def check_session_start_time_old_date(nwbfile: NWBFile):
     """
     session_start_time = nwbfile.session_start_time
     dummy_time = datetime(1980, 1, 1)
-    if session_start_time.tzinfo is not None:
-        dummy_time = dummy_time.astimezone()
+
+    tzinfo = session_start_time.tzinfo
+    if tzinfo is not None:
+        dummy_time = dummy_time.astimezone(tzinfo)
+
     if session_start_time <= dummy_time:
         return InspectorMessage(
             message=(f"The session_start_time ({session_start_time}) may not be set to the true date of the recording.")
@@ -45,8 +48,10 @@ def check_session_start_time_future_date(nwbfile: NWBFile):
     """
     session_start_time = nwbfile.session_start_time
     current_time = datetime.now()
+    tzinfo = session_start_time.tzinfo
     if session_start_time.tzinfo is not None:
-        current_time = current_time.astimezone()
+        current_time = current_time.astimezone(tzinfo)
+
     if session_start_time >= current_time:
         return InspectorMessage(
             message=f"The session_start_time ({session_start_time}) is set to a future date and time."