[2.5] Bump up python version of Dockerfile

[IsaacYangSLA]

Description

This PR is to update the dockerfile which builds the docker image for dashboard.

Types of changes

• [x] Non-breaking change (fix or new feature that would not break existing functionality).
• [ ] Breaking change (fix or new feature that would cause existing functionality to change).
• [ ] New tests added to cover the changes.
• [x] Quick tests passed locally by running ./runtest.sh.
• [ ] In-line docstrings updated.
• [ ] Documentation updated.

[IsaacYangSLA]

/build