Pull requests merging `production` into a branch auto-deploy an invalid instance

[grantfitzsimmons]

This pull request caused a massive issue as the test panel would auto-deploy it, assuming that production was a tag on our docker hub. Of course, that was not the case, so it would error if it ever tried to deploy anything.

When attempting to run the compose process:

ERROR: manifest for specifyconsortium/specify7-service:production not found: manifest unknown: manifest unknown

This prevented any new deployments from being created and introduced continuous problems

[grantfitzsimmons]

For reference, here are all of the tags we have on our DockerHub:
https://hub.docker.com/r/specifyconsortium/specify7-service/tags

[maxpatiiuk]

Yeah, production is a special branch and is available in docker as edge instead.

Need to modify the test server code to substitute that in the response received from github API (when fetching pull requests)