Update django-celery-beat from 2.5.0 to 2.6.0 (#4899)

Author: pyup-bot

{{cookiecutter.project_slug}}/requirements/base.txt

@@ -17,7 +17,7 @@ hiredis==2.3.2  # https://github.com/redis/hiredis-py
 {%- endif %}
 {%- if cookiecutter.use_celery == "y" %}
 celery==5.3.6  # pyup: < 6.0  # https://github.com/celery/celery
-django-celery-beat==2.5.0  # https://github.com/celery/django-celery-beat
+django-celery-beat==2.6.0  # https://github.com/celery/django-celery-beat
 {%- if cookiecutter.use_docker == 'y' %}
 flower==2.0.1  # https://github.com/mher/flower
 {%- endif %}