Django programming: cannot cast time without time zone to timestamp

I am newbie to django and was using SQLite during development, when i moved to postgres when trying to deploy to production i get the below error

Cannot cast type time without time zone to timestamp with time zone

settings.py

Django settings for todoBackend project.

Generated by 'django-admin startproject' using Django 3.2.5.

For more information on this file, see
https://docs.djangoproject.com/en/3.2/topics/settings/

For the full list of settings and their values, see
https://docs.djangoproject.com/en/3.2/ref/settings/
"""

from pathlib import Path
from django.core.management.utils import get_random_secret_key
import os
import sys
import dj_database_url

# Build paths inside the project like this: BASE_DIR / 'subdir'.
BASE_DIR = Path(__file__).resolve().parent.parent


# Quick-start development settings - unsuitable for production
# See https://docs.djangoproject.com/en/3.2/howto/deployment/checklist/

# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = os.getenv("DJANGO_SECRET_KEY", get_random_secret_key())

# SECURITY WARNING: don't run with debug turned on in production!

DEBUG = os.getenv("DEBUG", "False") == "True"

ALLOWED_HOSTS = os.getenv("DJANGO_ALLOWED_HOSTS", "127.0.0.1,localhost").split(",")

# Application definition


INSTALLED_APPS = [
    "rest_framework",
    "corsheaders",
    "api.apps.ApiConfig",
    "django.contrib.admin",
    "django.contrib.auth",
    "django.contrib.contenttypes",
    "django.contrib.sessions",
    "django.contrib.messages",
    "django.contrib.staticfiles",
]

MIDDLEWARE = [
    "corsheaders.middleware.CorsMiddleware",
    "django.middleware.common.CommonMiddleware",
    "django.middleware.security.SecurityMiddleware",
    "django.contrib.sessions.middleware.SessionMiddleware",
    "django.middleware.csrf.CsrfViewMiddleware",
    "django.contrib.auth.middleware.AuthenticationMiddleware",
    "django.contrib.messages.middleware.MessageMiddleware",
    "django.middleware.clickjacking.XFrameOptionsMiddleware",
]
CORS_ALLOW_ALL_ORIGINS = True
ROOT_URLCONF = "todoBackend.urls"

TEMPLATES = [
    {
        "BACKEND": "django.template.backends.django.DjangoTemplates",
        "DIRS": [],
        "APP_DIRS": True,
        "OPTIONS": {
            "context_processors": [
                "django.template.context_processors.debug",
                "django.template.context_processors.request",
                "django.contrib.auth.context_processors.auth",
                "django.contrib.messages.context_processors.messages",
            ],
        },
    },
]

WSGI_APPLICATION = "todoBackend.wsgi.application"


# Database
# https://docs.djangoproject.com/en/3.2/ref/settings/#databases

DEVELOPMENT_MODE = os.getenv("DEVELOPMENT_MODE", "False") == "True"
# DEVELOPMENT_MODE = True

if DEVELOPMENT_MODE is True:
    DATABASES = {
        "default": {
            "ENGINE": "django.db.backends.sqlite3",
            "NAME": os.path.join(BASE_DIR, "db.sqlite3"),
        }
    }
elif len(sys.argv) > 0 and sys.argv[1] != "collectstatic":
    if os.getenv("DATABASE_URL", None) is None:
        raise Exception("DATABASE_URL environment variable not defined")
    DATABASES = {
        "default": dj_database_url.parse(os.environ.get("DATABASE_URL")),
    }


# Password validation
# https://docs.djangoproject.com/en/3.2/ref/settings/#auth-password-validators

AUTH_PASSWORD_VALIDATORS = [
    {
        "NAME": "django.contrib.auth.password_validation.UserAttributeSimilarityValidator",
    },
    {
        "NAME": "django.contrib.auth.password_validation.MinimumLengthValidator",
    },
    {
        "NAME": "django.contrib.auth.password_validation.CommonPasswordValidator",
    },
    {
        "NAME": "django.contrib.auth.password_validation.NumericPasswordValidator",
    },
]


# Internationalization
# https://docs.djangoproject.com/en/3.2/topics/i18n/

LANGUAGE_CODE = "en-us"

TIME_ZONE = "Asia/Kolkata"

USE_I18N = True

USE_L10N = True

USE_TZ = True


# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/3.2/howto/static-files/

STATIC_URL = "/static/"
STATIC_ROOT = os.path.join(BASE_DIR, "staticfiles")
# Default primary key field type
# https://docs.djangoproject.com/en/3.2/ref/settings/#default-auto-field

DEFAULT_AUTO_FIELD = "django.db.models.BigAutoField"

models.py

from django.db import models

# Create your models here.
class Tasks(models.Model):
    title = models.CharField(max_length=200, blank=False, null=False)
    description = models.CharField(max_length=1000, blank=True)
    start_time = models.DateTimeField(blank=True, null=True)
    end_time = models.DateTimeField(blank=True, null=True)
    duration = models.CharField(max_length=25, blank=True)
    completed = models.BooleanField(default=False)
    last_modified = models.DateTimeField(auto_now=True)

    def __str__(self):
        return self.title

I am not sure why i am getting the error, i did setup the timezone in settings.py

The above code was working perfectly with SQLite , It only throws the error in Postgres