fix: timezone offset with old pytz and pandas

It seems that older pandas and pytz distributions (for example, ones
from Debian 10 deb repositories) are prone to issues when pytz timezone
offset ignores current datetime value [1]. Using explicit localize is
both valid in modern version and fixes the bug for older ones.

1. https://stackoverflow.com/questions/11473721/weird-timezone-issue-with-pytz

Part of #198

Author: DifferentialOrange

CHANGELOG.md

@@ -211,6 +211,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Puting test files in pip package (#238).
 - Make connection close idempotent (#250).
 - readthedocs version (#255).
+- timezone offset with old pytz and pandas (#198).
 
 ## 0.9.0 - 2022-06-20
 

Makefile

@@ -64,7 +64,7 @@ rpm-dist-check:
 
 .PHONY: deb-changelog-entry
 deb-changelog-entry:
-	DEBEMAIL=admin@tarantool.org dch --distribution unstable \
+	DEBEMAIL=admin@tarantool.org dch --distribution unstable -b \
 									 --package "python3-tarantool" \
 									 --newversion $$(python3 setup.py --version) \
 									 "Nightly build"

tarantool/msgpack_ext/types/datetime.py

@@ -291,9 +291,9 @@ def __init__(self, *, timestamp=None, year=None, month=None,
                 datetime = pandas.to_datetime(timestamp, unit='s')
 
             if not timestamp_since_utc_epoch:
-                self._datetime = datetime.replace(tzinfo=tzinfo)
+                self._datetime = datetime.tz_localize(tzinfo)
             else:
-                self._datetime = datetime.replace(tzinfo=pytz.UTC).tz_convert(tzinfo)
+                self._datetime = datetime.tz_localize(pytz.UTC).tz_convert(tzinfo)
         else:
             if nsec is not None:
                 microsecond = nsec // NSEC_IN_MKSEC
@@ -306,7 +306,7 @@ def __init__(self, *, timestamp=None, year=None, month=None,
                 year=year, month=month, day=day,
                 hour=hour, minute=minute, second=sec,
                 microsecond=microsecond,
-                nanosecond=nanosecond, tzinfo=tzinfo)
+                nanosecond=nanosecond).tz_localize(tzinfo)
 
     def _interval_operation(self, other, sign=1):
         """