Switch to preshed v4

[adrianeboyd]

Description

Switch to preshed v4.

Types of change

Enhancement?

Checklist

• [x] I confirm that I have the right to submit this contribution under the project's MIT license.
• [x] I ran the tests, and all new and existing tests passed.
• [x] My changes don't require a change to the documentation, or if they do, I've added all required information.

[adrianeboyd]

The idea here was to release the next version of thinc v9.0.0.devN so that we can use this in spacy v4, however preshed v4.0.0 seems to fail immediately in the tokenizer cache, so we'll put this on hold until we figure out what's going on.