v0.9.1

• Bugfix: LruCache::contains_key should take &self and not move the entry as
  though it is accessed.
• Add basic CursorMut API to HashMap (thanks @olebedev!)
• Bump hashbrown dependency to depend on a version of hashbrown past a
  downstream zerocopy dependency.
• Don't depend on default features of hashbrown, removes allocator-api2
  dependency.