update `ard_cohens_d` function to accept multiple variables #374

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gitleaks 💧 / gitleaks 💧	7s
Coverage 📔 / Covtracer 🐄	0s
gitleaks 💧 / PII Check 💳	0s
Roxygen 🅾 / Manual pages check 🏁	2m 35s
Spell Check 🆎 / Check spelling 🔠	1m 43s
Check URLs 🌐 / Validate Links 🔎	7s
Version Check 🏁 / Version check 🏁	2s
Version Check 🏁 / Emoji in NEWS.md 📰	6s
Grammar Check 🔤 / Check 📝	11s
License Check 🃏 / Check 🚩	37s
Style Check 👗 / Check code style 🔠	1m 43s
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R CMD Check 🧬 / Upload build tar.gz	0s
R CMD Check 🧬 / Publish JUnit HTML report 📰	0s
	15m 2s

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