Update R-CMD-check.yaml

Remove ubuntu -- package will never be on CRAN, largely a data package

Author: ericward-noaa

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

@@ -20,9 +20,6 @@ jobs:
         config:
           - {os: macOS-latest,   r: 'release'}
           - {os: windows-latest, r: 'release'}
-          - {os: ubuntu-latest,   r: 'devel', http-user-agent: 'release'}
-          - {os: ubuntu-latest,   r: 'release'}
-          - {os: ubuntu-latest,   r: 'oldrel-1'}
 
     env:
       GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}