Update getrandom to 0.4

[KodrAus]

The changelog for getrandom suggests the major change here is a bump of the MSRV. I've already been on the fence about doing this for #852, so if it otherwise remains compatible, I think we can accept the bump and move all of these things forwards.

[KodrAus]

Also to check: whether Uuid::new_v4() on Windows is better without rand now that getrandom is using a different Windows API. If so, I'll deprecate that feature flag too.

[KodrAus]

Looks like rand itself doesn't depend on getrandom 0.4 yet, so I suspect this is blocked until its 0.10.0 release comes out.

[sabify]

@KodrAus The rand v0.10.0 has just been released.

[KodrAus]

Looks like we need to bump to 1.85.0 to support getrandom 0.4, since it's now using the 2024 Edition.

[sabify]

Thanks!

Can you please cut a new release?

[KodrAus]

@sabify I'd like to try get #852 into this release too to avoid needing to make too many too frequently. If that isn't merged in tomorrow though then I'll publish a new version then.