Missing rate limit in Authentication in bookwyrm

BookWyrm is a social network for tracking reading. Versions prior to 0.4.5 were found to lack rate limiting on authentication views which allows brute-force attacks. This issue has been patched in version 0.4.5. Admins with existing instances will need to update their `nginx.conf` file that was created when the instance was set up. Users are advised advised to upgrade. Users unable to upgrade may update their nginx.conf files with the changes manually.