[Release] macOS wheel verification also needs arrow-testing

[asfimport]

Without it, Flight tests error (with a misleading message)

Reporter: Neal Richardson / @nealrichardson
Assignee: Neal Richardson / @nealrichardson

PRs and other links:

• GitHub Pull Request #6345

_{Note: This issue was originally created as ARROW-7751. Please see the migration documentation for further details.}

[asfimport]

Krisztian Szucs / @kszucs:
Issue resolved by pull request 6345
#6345