When PUT or DELETE is called with non-existing user ID it still returns OK instead of error

Update edition and refactor project & code improvements

create docker file so we can run app in docker

Add integration tests as described at https://actix.rs/docs/testing/

Add github actions pipeline which will run tests, check and potentionally build

At the moment there is no way to configure application as all the values are hardcoded.
It would be good to have some kind of config structure that would load all the configuration and then pass it where it is needed. That way all the configurable data will be at one place and not scattered through whole code base.

Add basic authentication (for login) as well as JWT validation.

Add basic roles that will manage what user can do (ie user - create tickets and manage owned/assigned tickets, admin - manage tickets and users, inactive - cannot do anything)

It would be nice to be able to log actions that happened with each ticket and to also show them.
For example if ticket is assigned to someone or closed, this action should be logged on be available on the ticket.

Implement metrics collection and expose them so they can be scraped

• Rename metrics as described in best practices
• use labels
• use histogram for measuring request process times