PSA: uuid's getrandom update may break no-std V4/V7 users

See: https://github.com/uuid-rs/uuid/pull/793

I wanted to call out that as part of our getrandom update in uuid, which will be released as 1.13.0, users in no-std environments who have enabled the v4 or v7 features will likely be broken on update.

If you're using uuid in wasm32-unknown-unknown with the js feature, you shouldn't see any breakage.

The source of the problem is that we advertised getrandom as our source of randomness, pointing to its docs on setting a provider on otherwise unsupported platforms. That mechanism has changed between their 0.2 and 0.3 releases (as they're fully entitled to do), meaning we can't upgrade getrandom in uuid without propagating that breakage. It's not getrandom's fault. It's ours.

Affected users will be able to upgrade to getrandom 0.3 and use its new APIs, but this is not guaranteed to work forever. uuid needs to stop relying on it as a public dependency. If this affects you I'd appreciate if you'd comment on https://github.com/uuid-rs/uuid/issues/792 so we can explore ways to continue supporting you.