CLN: clean up ugly dateutil imports

Author: AlexKirko

pandas/_libs/tslibs/conversion.pyx

@@ -5,8 +5,7 @@ cimport numpy as cnp
 from numpy cimport int64_t, int32_t, intp_t, ndarray
 cnp.import_array()
 
-from dateutil.zoneinfo import tzfile as du_tzfile1
-from dateutil.tz.tz import tzfile as du_tzfile2
+from dateutil.tz import tzfile as _dateutil_tzfile
 
 import pytz
 
@@ -386,13 +385,13 @@ cdef _TSObject convert_datetime_to_tsobject(datetime ts, object tz,
     else:
         obj.value = pydatetime_to_dt64(ts, &obj.dts)
         # GH 24329 Take DST offset into account
-        # Two check in if necessary because class
-        # differs on Windows and Linux
-        if (isinstance(ts.tzinfo, du_tzfile1) or
-                isinstance(ts.tzinfo, du_tzfile2)):
-            if ts.tzinfo.is_ambiguous(ts):
-                dst_offset = ts.tzinfo.dst(ts)
-                obj.value += int(dst_offset.total_seconds() * 1e9)
+        # use get_dst_info to get type
+        if ts.tzinfo is not None:
+            trans, deltas, typ = get_dst_info(ts.tzinfo)
+            if isinstance(ts.tzinfo, _dateutil_tzfile):
+                if ts.tzinfo.is_ambiguous(ts):
+                    dst_offset = ts.tzinfo.dst(ts)
+                    obj.value += int(dst_offset.total_seconds() * 1e9)
         obj.tzinfo = ts.tzinfo
 
     if obj.tzinfo is not None and not is_utc(obj.tzinfo):