Fix CI tests

[markdboyd]

Changes proposed in this pull request:

Related to #97

• Updating Python version to match version in CI
• Fix bandit code scanning tests for CI
• Update setup environment script to install editable package for unit testing
• Removed unnecessary step from e2e tests
• Update proxy code to make certs optional for local testing
• Update config unit tests for new certificate properties

Things to check

• For any logging statements, is there any chance that they could be logging sensitive data?
• Are log statements using a logging library with a logging level set? Setting a logging level means that log statements "below" that level will not be written to the output. For example, if the logging level is set to INFO and debugging statements are written with log.debug or similar, then they won't be written to the otput, which can prevent unintentional leaks of sensitive data.

Security considerations

These changes are test facing and have no direct security impact