Review npm deprecation warnings

[willdurand]

npm WARN deprecated har-validator@5.1.5: this library is no longer supported
npm WARN deprecated uuid@3.4.0: Please upgrade  to version 7 or higher.  Older versions may use Math.random() in certain circumstances, which is known to be problematic.  See https://v8.dev/blog/math-random for details.
npm WARN deprecated request@2.88.2: request has been deprecated, see https://github.com/request/request/issues/3142

[willdurand]

The 3 warnings are all related to request@2, so we should probably replace request with... node-fetch?

[stale]

This issue has been automatically marked as stale because it has not had recent activity. If you think this bug should stay open, please comment on the issue with further details. Thank you for your contributions.

[lsim]

This may not look particularly urgent, but many CI pipelines are failing due to this since npm audit fails for repos that publish firefox extensions.

% yarn audit                                                                                                                                                                                            23-06-06 - 10:40:51
yarn audit v1.22.19
┌───────────────┬──────────────────────────────────────────────────────────────┐
│ moderate      │ Server-Side Request Forgery in Request                       │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Package       │ request                                                      │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Patched in    │ No patch available                                           │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Dependency of │ web-ext                                                      │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ Path          │ web-ext > sign-addon > request                               │
├───────────────┼──────────────────────────────────────────────────────────────┤
│ More info     │ https://www.npmjs.com/advisories/1091725                     │
└───────────────┴──────────────────────────────────────────────────────────────┘
1 vulnerabilities found - Packages audited: 895
Severity: 1 Moderate