Updated `ard_wilcoxtest()` to allow multiple variables #161

All 20 tests pass, 8 skipped in 4s

1 files ±0 29 suites ±0 4s ⏱️ ±0s
28 tests ±0 20 ✅ ±0 8 💤 ±0 0 ❌ ±0
71 runs ±0 52 ✅ ±0 19 💤 ±0 0 ❌ ±0

Results for commit 60d9824. ± Comparison against earlier commit 888557f.