More robut session fixture

[bmos]

What's Changed

• Refactor session and driver creation to better handle errors
• Run ruff format to remove whitespace from empty line
• In tests that don't rely on session fixture, add check for discarded browser context
• List each test result individually in github actions log
• Opt-in to Selenium 5 default behavior (upgrading webdriver to match selenium version) in github actions workflow

Why?

Remaining intermittent test failures occur during session object creation

[github-actions]

Coverage report

This PR does not seem to contain any modification to coverable code.

[bmos]

I'm going to run the tests a bunch of times sequentially on my fork to see if they pass consistently to really make sure I get all the intermittent failure modes.