Update to pa11y v8 and other dependency updates

[aarongoldenthal]

This PR updates pa11y to v8 (required for #232) and all other dependencies to the latest supported, applicable versions (unless otherwise noted). Several of these had breaking changes, as noted (all resolved). It also adds test for Node 22.

Dependencies

• Updated pa11y from 7.0.0 to 8.0.0.
• Updated commander from 11.1.0 to 12.1.0 (BREAKING changes):
  • Updated to use named export and instantiate a new Command.
• Updated puppeteer from 20.9.0 to 22.12.1 (BREAKING changes):
  • Renamed createIncognitoBrowserContext to createBrowserContext.
  • Enables the new-headless mode by default.
  • Updated integration tests error message from "timed out" to "timeout".
  • Updated integration test timeout to 30s to resolve some intermittent timeout issues with before hooks.

Dev Dependencies

• Updated mocha from 10.3.0 to 10.6.0
• Updated eslint from 8.56.0 to 8.57.0, but not v9.
  • Update to v9 should include updating pa11y-lint-config to flat config since the legacy config format is now deprecated.
• Updated sinon from 17.0.1 to 18.0.0.
• Updated nyc from 15.1.0 to 17.0.0 (only breaking change is compatible Node versions).

Actions

• Added tests with Node 22 (released 2024-04-24).

Not Updated

• globby was not updated due to breaking behavioral changes in subsequent versions.
• node-fetch was not updated since all updates are pure ESM only.
  • Node's fetch API is not stable until Node 21 (per the docs). This is only used to fetch sitemaps, but I held off since the LTS releases are still not stable.
• protocolify was not updated since all updates are pure ESM only.