chore: update dependencies (including circle -> gha)

[dbjorge]

Test run: https://github.com/dequelabs/dbjorge-test-repo/actions/runs/9604481533/job/26490058201

Notes on the updates:

• I blew away the whole lockfile and updated everything listed in package.json to latest
• ...except eslint, which I left at major version 8 for compat with typescript-eslint's current stable version
• ...and except a few dev deps that I dropped because we weren't using them anyway (eslint+tslint stuff, sinon)
• The octokit update bumps octokit to a version that uses native fetch, which nock can't mock, so I added a test seam that forces octokit to use node-fetch when NODE_ENV === 'test'. The alternatives would be to use a beta version of nock (didn't want to use a beta version of anything in a repo we update so rarely) or to use a different mocking library (fetch-mock was the best-looking option but it required more test changes than I wanted to spend time on to swap it out)

I included a conversion from circle to GHA because I hit errors when naively updating the circle config to node 20 and it was faster to convert than to debug circle. None of the failed checks are relevant anymore; once this merges we can disable circle in this repo and update the branch policies to refer to GHA.

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[scurker]

huh, interesting

[scurker]

🚨 Reviewed for Security 🚨