Update to latest rust nightly

[roblabla]

There are several bugs that got fixed in latest rust nightlies that will allow us to remove various hacks and workarounds:

• Added ability to crosscompile doctests rust-lang/cargo#6892 means we can remove the testinner rule from our makefile
• Force clippy to run. rust-lang/cargo#7157 means we can remove the refresh-crates rule from our makefile
• Various futures fixes means we can remove the HRTB hack from libuser/src/ipc/server.rs
• Enable if and match in constants behind a feature flag rust-lang/rust#66507 means we can now use if/match in const fn, which should allow us to make pack/unpack much faster
• Add new EFIAPI ABI rust-lang/rust#65809 unlocks progress on an EFI bootloader.

There's probably more.