fix: change the R version

Author: jakwisn

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

@@ -35,15 +35,11 @@ jobs:
           - {os: windows-latest, r: '4.1'}
           - {os: windows-latest, r: '4.0'}
           - {os: windows-latest, r: '3.6'}
-          - {os: windows-latest, r: '3.5'}
           - {os: macOS-latest,   r: '4.1'}
           - {os: macOS-latest,   r: '4.0'}
-          - {os: macOS-latest,   r: '3.6'}
           - {os: ubuntu-18.04, r: '4.1', vdiffr: true,  xref: true, rspm: "https://packagemanager.rstudio.com/cran/__linux__/bionic/latest"}
           - {os: ubuntu-18.04, r: '4.0', vdiffr: true,  xref: true, rspm: "https://packagemanager.rstudio.com/cran/__linux__/bionic/latest"}
           - {os: ubuntu-18.04, r: '3.6', vdiffr: true,  xref: true, rspm: "https://packagemanager.rstudio.com/cran/__linux__/bionic/latest"}
-          - {os: ubuntu-18.04, r: '3.5', vdiffr: true,  xref: true, rspm: "https://packagemanager.rstudio.com/cran/__linux__/bionic/latest"}
-
 
     env:
       R_REMOTES_NO_ERRORS_FROM_WARNINGS: true