simpler workflow

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

@@ -1,9 +1,5 @@
 # Workflow derived from https://github.com/r-lib/actions/tree/v2/examples
 # Need help debugging build failures? Start at https://github.com/r-lib/actions#where-to-find-help
-#
-# NOTE: This workflow is overkill for most R packages and
-# check-standard.yaml is likely a better choice.
-# usethis::use_github_action("check-standard") will install it.
 on:
   push:
     branches: [main, master]
@@ -23,19 +19,10 @@ jobs:
       matrix:
         config:
           - {os: macos-latest,   r: 'release'}
-
           - {os: windows-latest, r: 'release'}
-          # Use 3.6 to trigger usage of RTools35
-          - {os: windows-latest, r: '3.6'}
-          # use 4.1 to check with rtools40's older compiler
-          - {os: windows-latest, r: '4.1'}
-
           - {os: ubuntu-latest,   r: 'devel', http-user-agent: 'release'}
           - {os: ubuntu-latest,   r: 'release'}
           - {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 }}