don't do oldrel-4

Author: EmilHvitfeldt

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

@@ -34,7 +34,6 @@ jobs:
           - {os: ubuntu-latest,  r: 'oldrel-1'}
           - {os: ubuntu-latest,  r: 'oldrel-2'}
           - {os: ubuntu-latest,  r: 'oldrel-3'}
-          - {os: ubuntu-latest,  r: 'oldrel-4'}
 
     env:
       GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}