Fix go version issue in test

[acheong08]

golang/go#57433

slices in the standard library has only existed since go1.21. This is the reason for the errors in the recent tests.

You have the following options:

• Use golang.org/x/exp/slices instead. This allows compatibility with go1.20 and below.
• Make sure to only use go1.21 in your tests.

This does not fix everything wrong with the tests. Most errors come from gocloud.dev/pubsub/drivertest.

e.g.

    drivertest.go:564: nats: API error: code=400 err_code=10128 description=Stream name can not contain path separators

It looks like the issue has to do with t.Name() returning either the full or relative path as part of the name.

There are a lot more issues than $27 is worth lol. Just a fun rabbit hole I saw on Replit.