tools: remove unused timestamp_to_datetime (#31950)

tools/lib/helpers.py

@@ -1,7 +1,4 @@
 import bz2
-import datetime
-
-TIME_FMT = "%Y-%m-%d--%H-%M-%S"
 
 
 # regex patterns
@@ -23,13 +20,6 @@ class RE:
   OP_SEGMENT_DIR = fr'^(?P<segment_name>{SEGMENT_NAME})$'
 
 
-def timestamp_to_datetime(t: str) -> datetime.datetime:
-  """
-    Convert an openpilot route timestamp to a python datetime
-  """
-  return datetime.datetime.strptime(t, TIME_FMT)
-
-
 def save_log(dest, log_msgs, compress=True):
   dat = b"".join(msg.as_builder().to_bytes() for msg in log_msgs)