Problem Installing from Docker

Hi there!

I'm having a problem installing bilm-tf from the docker image according to the instructions from README.

I'm getting an old image that throws an error that was fixed in October 2018, because of the following line:
[code[k + 1] = self.eow_char](https://github.com/allenai/bilm-tf/pull/83/files)

I have two other machines running this image and they look updated, but for some reason this setup I'm running today is giving me this deprecated code.

How can I make sure I'm running a docker container with the latest code?

Thanks!