Pinned Python 2 CI tests to legacy version of dependencies

[danielmorell]

Description of the change

certifi is a package that helps validate SSL root certificates that we depend on. In the latest release it started using Python 3 syntax. Since we have always been using the latest version, our Python 2 CI tests started failing after the last release of certifi.

This PR pip installs certifi==2021.10.8 if our CI test matrix is testing on Python 2.7. This is not an ideal solution seeing that we will not be using up to date root certificates in our tests. However, that may be a compromise we are willing to make.

Type of change

• [ ] Bug fix (non-breaking change that fixes an issue)
• [ ] New feature (non-breaking change that adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [x] Maintenance
• [ ] New release

Related issues

None (see our latest failed action run)

Checklists

Development

• [x] Lint rules pass locally
• [ ] The code changed/added as part of this pull request has been covered with tests
• [ ] All tests related to the changed code pass in development

Code review

• [ ] This pull request has a descriptive title and information useful to a reviewer. There may be a screenshot or screencast attached
• [ ] "Ready for review" label attached to the PR and reviewers assigned
• [ ] Issue from task tracker has a link to this pull request
• [ ] Changes have been reviewed by at least one other engineer

[danielmorell]

Yeah. Not having up to date SSL root certs is kind of a big deal. I haven't thought of any great way to solve that.