[clojure-emacs/cider#1825] Adapt to latest test.check

[sebastianpoeplau]

Before submitting a PR make sure the following things have been done:

• The commits are consistent with our contribution guidelines
• You've added tests to cover your change(s)
• All tests are passing
• The new code is not generating reflection warnings
• You've updated the readme (if adding/changing middleware)

Thanks!

test.check now reports minimal failing inputs (clojure/test.check@73b12bc).