Update R-CMD-check.yml

Add testing for Debian

Author: NightlordTW

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

@@ -23,6 +23,7 @@ jobs:
           - {os: ubuntu-latest,   r: 'devel', http-user-agent: 'release'}
           - {os: ubuntu-latest,   r: 'release'}
           - {os: ubuntu-latest,   r: 'oldrel-1'}
+          - {os: debian-latest,   r: 'release'} 
 
     env:
       GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}