Add conditional so that we only create the folder when media is served by nginx Docker service

from project-generationx-options.rst -> "If you choose no cloud provider and docker, the production stack will serve the media files via an nginx Docker service"

{{cookiecutter.project_slug}}/compose/production/django/Dockerfile

@@ -119,8 +119,10 @@ COPY --from=client-builder --chown=django:django ${APP_HOME} ${APP_HOME}
 COPY --chown=django:django . ${APP_HOME}
 {%- endif %}
 
+{%- if cookiecutter.cloud_provider == 'None' %} 
 # explicitly create the media folder before changing ownership below
 RUN mkdir -p ${APP_HOME}/{{ cookiecutter.project_slug }}/media
+{%- endif %}
 
 # make django owner of the WORKDIR directory as well.
 RUN chown -R django:django ${APP_HOME}