From 4b147004f379e7f62bba64b557c3df633ca1fa42 Mon Sep 17 00:00:00 2001
From: Chris Modzelewski <chris@highchartspython.com>
Date: Wed, 12 Jul 2023 15:52:28 -0400
Subject: [PATCH 1/2] Fixed reference to datetime.timezone.

---
 highcharts_gantt/options/series/data/gantt.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/highcharts_gantt/options/series/data/gantt.py b/highcharts_gantt/options/series/data/gantt.py
index df93d1a..e15503c 100644
--- a/highcharts_gantt/options/series/data/gantt.py
+++ b/highcharts_gantt/options/series/data/gantt.py
@@ -1,6 +1,6 @@
 from typing import Optional, List
 from decimal import Decimal
-from datetime import datetime, date
+from datetime import datetime, date, timezone
 
 from validator_collection import validators, checkers
 
@@ -346,13 +346,13 @@ def _to_untrimmed_dict(self, in_cls = None) -> dict:
 
         if self.end is not None and hasattr(self.end, 'timestamp'):
             if not self.end.tzinfo:
-                self.end = self.end.replace(tzinfo = datetime.timezone.utc)
+                self.end = self.end.replace(tzinfo = timezone.utc)
             untrimmed['end'] = self.end.timestamp() * 1000
         else:
             untrimmed['end'] = self.end
         if self.start is not None and hasattr(self.start, 'timestamp'):
             if not self.start.tzinfo:
-                self.start = self.start.replace(tzinfo = datetime.timezone.utc)
+                self.start = self.start.replace(tzinfo = timezone.utc)
 
             untrimmed['start'] = self.start.timestamp() * 1000
         else:

From 8b2bbde1227416499be56d2a3df0ee46c4ffae65 Mon Sep 17 00:00:00 2001
From: Chris Modzelewski <chris@highchartspython.com>
Date: Wed, 12 Jul 2023 15:52:38 -0400
Subject: [PATCH 2/2] Bumped version number and changelog.

---
 CHANGES.rst                     | 7 +++++++
 highcharts_gantt/__version__.py | 2 +-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/CHANGES.rst b/CHANGES.rst
index 642d9d5..abec9ff 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,3 +1,10 @@
+Release 1.2.3
+=========================================
+
+* **BUGFIX:** Fixed refernece bug in serialization of ``GanttData`` instances with timezone-naive ``datetime`` instances in ``start and ``end``.
+
+------------------
+
 Release 1.2.2
 =========================================
 
diff --git a/highcharts_gantt/__version__.py b/highcharts_gantt/__version__.py
index 923b987..5a5df3b 100644
--- a/highcharts_gantt/__version__.py
+++ b/highcharts_gantt/__version__.py
@@ -1 +1 @@
-__version__ = '1.2.2'
+__version__ = '1.2.3'