Upgrade to redb 0.11.0

[cberner]

I haven't finished benchmarking the mmap backend against the new safe one, so I left ord using the mmap backend.

[casey]

Nice! Thanks for the PR! Can AccessGuard<T> implement Deref<T>? Not sure if this is possible, but if it were, it might make them slightly more convenient.

[cberner]

I don't think that's possible today, because .value() returns the lifetime of &self. If they have a LendingDeref in the future that would work though.

[casey]

Can't Deref::deref borrow &self?

The trait is fn deref(&self) -> &Self::Target; which has an elided lifetime, so it's actually fn deref<'a>(&'a self) -> &'a Self::Target;

[cberner]

oh right, duh. I mixed this up with a different issue I had =P The problem with Deref is that it returns &Self::Target, but I need to return Self::Target for types like u64