update `strata` var to `group_var` #3123

Job	Run time
Version Bump 🤜🤛	0s
Audit Dependencies 🕵️‍♂️ / oysteR scan 🦪	1m 41s
SuperLinter 🦸‍♀️ / SuperLinter 🦸‍♂️	1m 25s
SuperLinter 🦸‍♀️ / Lint R code 🧶	2m 7s
R CMD Check 🧬 / ghcr.io/insightsengineering/rstudio, version latest	1h 18m 12s
Coverage 📔 / Coverage 📔	9m 47s
R CMD Check (non-CRAN) 🧬 / ghcr.io/insightsengineering/rstudio, version latest	12m 3s
Coverage 📔 / Covtracer 🐄	0s
gitleaks 💧 / PII Check 💳	0s
gitleaks 💧 / gitleaks 💧	10s
Grammar Check 🔤 / Check 📝	9s
License Check 🃏 / Check 🚩	32s
Check URLs 🌐 / Validate Links 🔎	0s
Check URLs 🌐 / URL Checker 🔎	49s
Roxygen 🅾 / Manual pages check 🏁	8m 24s
Style Check 👗 / Check code style 🔠	1m 41s
Spell Check 🆎 / Check spelling 🔠	1m 41s
Version Check 🏁 / Emoji in NEWS.md 📰	5s
Version Check 🏁 / Version check 🏁	6s
Coverage 📔 / Publish coverage report 📰	0s
R CMD Check (non-CRAN) 🧬 / Upload build tar.gz	0s
R CMD Check (non-CRAN) 🧬 / Publish JUnit HTML report 📰	0s
R CMD Check 🧬 / Publish JUnit HTML report 📰	0s
R CMD Check 🧬 / Upload build tar.gz	0s
	1h 58m 52s

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