Fix model directory in docker file

[MaHaWo]

Describe the bug
Dockercontainers running on the current image will not find models when the model directory of the container is mounted into an empty directory.

To Reproduce
Run the docker image with -v ~/faunanet/models:/root/faunanet/models for instance and observe that if the ~/faunanet/models models directory is empty the faunanet process will crash with an error indicating that no models have been found.

Expected behavior
default models should run irrespective of mounted directories or volumes.

machine/OS:

• OS: Linux, macOS, Windows