test: installing usethis

Author: ColinFay

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

@@ -42,7 +42,9 @@ jobs:
 
       - uses: r-lib/actions/setup-r-dependencies@v2
         with:
-          extra-packages: any::rcmdcheck
+          extra-packages: |
+            any::rcmdcheck
+            any::usethis
           needs: check
 
       - uses: r-lib/actions/check-r-package@v2