Flaky MacOS test suite

The CI test suite intermittently fails on MacOS due to what looks like a race condition:

```
npm ERR! code 1
npm ERR! path /Users/runner/work/combobox-nav/combobox-nav/node_modules/chromium
npm ERR! command failed
npm ERR! command sh -c node install.js
npm ERR! Step 1. Retrieving Chromium revision number
npm ERR! Step 2. Downloading Chromium revision 1025666
npm ERR! /Users/runner/work/combobox-nav/combobox-nav/node_modules/p-cancelable/index.js:48
npm ERR! throw new Error('The `onCancel` handler was attached after the promise settled.');
npm ERR! ^
npm ERR!
npm ERR! Error: The `onCancel` handler was attached after the promise settled.
npm ERR! at onCancel (/Users/runner/work/combobox-nav/combobox-nav/node_modules/p-cancelable/index.js:48:12)
npm ERR! at makeRequest (/Users/runner/work/combobox-nav/combobox-nav/node_modules/got/dist/source/as-promise/index.js:38:13)
npm ERR! at Request. (/Users/runner/work/combobox-nav/combobox-nav/node_modules/got/dist/source/as-promise/index.js:143:17)
npm ERR! at Object.onceWrapper (node:events:642:26)
npm ERR! at Request.emit (node:events:527:28)
npm ERR! at Timeout.retry (/Users/runner/work/combobox-nav/combobox-nav/node_modules/got/dist/source/core/index.js:1278:30)
npm ERR! at listOnTimeout (node:internal/timers:55[9](https://github.com/github/combobox-nav/runs/7410232560?check_suite_focus=true#step:4:10):17)
npm ERR! at processTimers (node:internal/timers:502:7)
npm ERR! A complete log of this run can be found in:
npm ERR! /Users/runner/.npm/_logs/2022-07-19T[13](https://github.com/github/combobox-nav/runs/7410232560?check_suite_focus=true#step:4:14)_32_24_7[14](https://github.com/github/combobox-nav/runs/7410232560?check_suite_focus=true#step:4:15)Z-debug-0.log
```

This doesn't happen on Ubuntu/Windows.

Start with the linked MacOS CI run and the npm install step that downloads Chromium revision 1025666. Compare the failing MacOS setup with the Ubuntu and Windows runs, focusing on the p-cancelable and got error shown in the log. Done means the MacOS test suite completes reliably without this intermittent installation failure.

Written by the indexing model from the issue text.