Fix strings2array

[svlandeg]

Description

As noted by Daniel in #917, an error crept in the forward function of strings2arrays: it shouldn't use asarray2i as introduced by #897. The bug at the time wasn't noticed because the slow tests weren't run. For now, this PR also removes the slow marker on the basic tagger's test_small_end_to_end test, to ensure any regressions would be visible quickly.

Types of change

bug fix

Checklist

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

[netlify]

👷 Deploy request for thinc-ai pending review.

Visit the deploys page to approve it

Name	Link
🔨 Latest commit	b750e98