Allow changing the password with the gotify/server cli

**Have you read the documentation?**
- [x] Yes, but it does not include related information regarding my question.
- [ ] Yes, but the steps described in the documentation do not work on my machine.
- [ ] Yes, but I am having difficulty understanding it and wants clarification.

**You are setting up gotify in**
- [x] Docker
- [ ] Linux native platform
- [ ] Windows native platform

**Describe your problem**
I have root access to the machine where gotify is running, but i forgot my user and password. How can I reset them?