Add update_repositories script to simulacrum for docker #106
Description
If users are not building the docker container on they're local machine and are instead pulling from dockerhub then they will have fixed versions of the dependency repos (LCLS-tools, LCLS-lattice, etc.)
To ensure that these repositories can be updated for any static docker image, a script can be added that pulls the main branches of the repos and reinstalls them to local python packages in the docker container.
This issue is part of a wider fix which will allow automated building and pushing of the simulacrum docker image using Github Actions.