Description of the change

This PR updates CI to include Rails 7.1, and fixes a compatibility issue with DebugExceptions#render_exception.

This PR also includes CI updates required to update from Ubuntu 18.04 to 20.04 in Github Actions.

Type of change

• Bug fix (non-breaking change that fixes an issue)
• Maintenance

Related issues

Fixes: #1122

Development

• 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