Switch to gunicorn

Historically, this repo has used waitress
instead of gunicorn which I am more familiar with.
This dates back to when Micah set this repo up.

However, I get alerted when the site goes down or has issues.
Since switching to Fly and more specifically since having
the async views, I've seen some issues on Fly with the site.

I'm hoping by using gunicorn with some limits
that the issues go away.

Author: davidfischer

Dockerfile

@@ -45,5 +45,4 @@ RUN date -u +'%Y-%m-%dT%H:%M:%SZ' > BUILD_DATE
 
 EXPOSE 8000
 
-# Increase the timeout since these PDFs take a long time to generate
-CMD ["waitress-serve", "--port=8000", "config.wsgi:application"]
+CMD ["gunicorn", "--timeout", "15", "--bind", ":8000", "--workers", "2", "--max-requests", "10000", "--max-requests-jitter", "100", "config.wsgi"]

requirements/common.txt

@@ -7,7 +7,7 @@ Django==3.2.18
 pytz==2022.7.1
 
 # A zero dependency WSGI server
-waitress==2.1.2
+gunicorn==20.1.0
 
 # For connecting to various APIs (eg. Meetup.com)
 requests==2.22.0