Switch branch on Heroku to main

[falonofthetower]

https://help.heroku.com/O0EXQZTA/how-do-i-switch-branches-from-master-to-main

Also update: bin/deploy.sh

[Code47X]

If "main" is this repo's root branch, are we good to remove "master" branch? Both are present currently in gh.

[aterrype]

Yeah, we should be good to remove master. I renamed it a while ago but forgot to remove it.