try ci on mac

Author: dajmcdon

.github/workflows/R-CMD-check.yaml

@@ -8,7 +8,7 @@ name: R-CMD-check
 
 jobs:
   R-CMD-check:
-    runs-on: ubuntu-latest
+    runs-on: macOS-latest
     env:
       GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
       R_KEEP_PKG_SOURCE: yes