update action with ubuntu

Author: rvalavi

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

@@ -6,7 +6,7 @@ on:
 name: R-CMD-check
 jobs:
   R-CMD-check:
-    runs-on: macOS-latest
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
       - uses: r-lib/actions/setup-r@v2