Replace new Traefik rules for entrypoint declaration

[kitos9112]

Recent releases of TRaefik (>=2.7.0) deprecated the use of their internal Rules struct so that's no longer available and needs to be refactored to support the new model.

Affected files:

• internal/server.go
• internal/server_test.go

Traefik source code:

https://github.com/traefik/traefik/blob/master/pkg/rules/parser.go

Block post announcement:
https://traefik.io/blog/announcing-traefik-proxy-2-7/