Ensure create_virtualenv.sh works with pyenv

[davidsmejia]

Context

While debugging the build of docker images on GHA I encountered an issue with running the create_virtualenv.sh script. It seems to not consistently put me in the dr_env virtualenv after execution. Additionally, it looks like there may be some inconsistencies with the version of pip used in the docker containers and the virtualenv leading to the build errors.

Solution or next step

• test a script that runs and builds requirements.txt based off of the same python base image that is used in the application
• Review the create_virtualenv.sh script to ensure that it does as described