After an embarrassingly long time, I figured out how to reset a password on a GoToSocial instance. You have to run the reset command, **AND THEN RESTART THE SERVER**.
It was that last part that tripped me up. I stopped reading after the password reset command. Oops.
From inside the docker container:
`./gotosocial admin account password --username USERNAME --password PASSWORD --config-path config.yaml`
The exit out of the container and run
`docker restart gotosocial`