ci: Check tarball size

Author: krlmlr

.github/workflows/install/action.yml

@@ -56,6 +56,7 @@ runs:
         echo "_R_CHECK_UNDOC_USE_ALL_NAMES_=true" | tee -a $GITHUB_ENV
         echo "_R_CHECK_URLS_SHOW_301_STATUS_=true" | tee -a $GITHUB_ENV
         echo "_R_CXX_USE_NO_REMAP_=true" | tee -a $GITHUB_ENV
+        echo "_R_CHECK_CRAN_INCOMING_=true" | tee -a $GITHUB_ENV
       shell: bash
 
     - name: Set environment variables (non-Windows only)