Update R-CMD-check.yaml

temporarily disable {os: macOS-latest,   r: 'devel'} due to r-lib/actions#140

Author: jgabry

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

@@ -19,7 +19,7 @@ jobs:
       fail-fast: false
       matrix:
         config:
-          - {os: macOS-latest,   r: 'devel'}
+          # - {os: macOS-latest,   r: 'devel'}
           - {os: macOS-latest,   r: 'release'}
           - {os: windows-latest, r: 'release'}
           - {os: ubuntu-16.04,   r: 'release', rspm: "https://packagemanager.rstudio.com/cran/__linux__/xenial/latest"}