Fix for git related error for jupyter notebooks running from docker container

[tanwarsh]

ISSUE :

• ERROR: Error [Errno 2] No such file or directory: 'git' while executing command git version
• ERROR: Cannot find command 'git' - do you have 'git' installed and in your PATH?

STEPS TO REPRODUCE :

• Create docker image for openFL
• Run openFL in a docker container
• Run jupyter notebooks in experimental folder which require pulling openfl code using git eg. Workflow_Interface_101_MNIST.ipynb

FIX DESCRIPTION / SUMMARY OF CHANGES:

• Added git to docker image
  Before:

After: