TLS certificates don't persist

As stated in the wiki caddy requests a new certificate because the caddy data isn't persisted through restarts. Is this behavior intended? Because it shouldn't be much work to make the data persist. I think the issue is that the target location of the bind mount at https://github.com/codalab/codabench/blob/ee8cdbcfb166d43ed5137c0c2b8897426091d836/docker-compose.yml#L14 points to the wrong location and an environment variable should be set so that it works, as stated in the caddy container's instructions.

On my fork I also upgraded to Caddy 2 but the change to make it persist was to simply fix the bind mount location (https://github.com/curious-broccoli/codabench/commit/d8114bfe3a009827384f3182ded91e365e80d7a5) and it seems to work.