[WEB-3087] fix: handle cycle start and end timezone conversion in list, create, and update (#6366)

* chore: handled cycle start and start timezone conversion in list, create and update

* chore: yarn lock

Author: gurusainath

apiserver/plane/app/serializers/cycle.py

@@ -22,7 +22,7 @@ def validate(self, data):
         ):
             project_id = (
                 self.initial_data.get("project_id", None)
-                or (self.instance and self.instance.get("project_id", None))
+                or (self.instance and self.instance.project_id)
                 or self.context.get("project_id", None)
             )
             is_start_date_end_date_equal = (

apiserver/plane/app/views/cycle/base.py

@@ -303,6 +303,11 @@ def create(self, request, slug, project_id):
                     .first()
                 )
 
+                datetime_fields = ["start_date", "end_date"]
+                cycle = user_timezone_converter(
+                    cycle, datetime_fields, request.user.user_timezone
+                )
+
                 # Send the model activity
                 model_activity.delay(
                     model_name="cycle",
@@ -387,6 +392,11 @@ def partial_update(self, request, slug, project_id, pk):
                 "created_by",
             ).first()
 
+            datetime_fields = ["start_date", "end_date"]
+            cycle = user_timezone_converter(
+                cycle, datetime_fields, request.user.user_timezone
+            )
+
             # Send the model activity
             model_activity.delay(
                 model_name="cycle",