Update GHA

Author: jeroen

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

@@ -22,7 +22,6 @@ jobs:
           - {os: ubuntu-latest,   r: 'devel', http-user-agent: 'release'}
           - {os: ubuntu-22.04,   r: 'release'}
           - {os: ubuntu-20.04,   r: 'release'}
-          - {os: ubuntu-18.04,   r: 'release'}
 
     env:
       GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
@@ -31,6 +30,12 @@ jobs:
     steps:
       - uses: actions/checkout@v3
 
+      - if: runner.os == 'windows'
+        run: choco uninstall rtools
+
+      - if: runner.os == 'windows' && matrix.config.r == '4.1'
+        uses: r-windows/install-rtools@master
+
       - if: matrix.config.os == 'ubuntu-18.04'
         run: sudo add-apt-repository ppa:cran/opencv-3.4