Add a job on Windows + R 4.1

The encoding improvements in R 4.2 on Windows mean that I really need to include 4.1 to make sure I can see the problem and that I have fixed it.

Also make the GHA config more obvious in other ways.

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

@@ -25,6 +25,8 @@ jobs:
  - {os: macOS-latest, r: 'release'}
 
  - {os: windows-latest, r: 'release'}
+ # Use 4.1 to trigger usage of RTools40
+ - {os: windows-latest, r: '4.1'}
  # Use 3.6 to trigger usage of RTools35
  - {os: windows-latest, r: '3.6'}
 
@@ -35,7 +37,8 @@ jobs:
  - {os: ubuntu-18.04, r: 'oldrel-2'}
  - {os: ubuntu-18.04, r: 'oldrel-3'}
  - {os: ubuntu-18.04, r: 'oldrel-4'}
- - {os: ubuntu-18.04, r: 'release', cran: "https://demo.rstudiopm.com/all/__linux__/bionic/latest", locale: 'en_US'}
+ # Check with a non-UTF-8 encoding
+ - {os: ubuntu-18.04, r: 'release', cran: "https://demo.rstudiopm.com/all/__linux__/bionic/latest", locale: 'en_US.ISO-8859-1'}
 
  env:
  GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
@@ -45,10 +48,10 @@ jobs:
  - uses: actions/checkout@v2
 
  - name: Set locale
- if: matrix.config.locale == 'en_US'
+ if: matrix.config.locale == 'en_US.ISO-8859-1'
  run: |
- sudo locale-gen en_US
- echo "LC_ALL=en_US" >> $GITHUB_ENV
+ sudo locale-gen en_US.ISO-8859-1
+ echo "LC_ALL=en_US.ISO-8859-1" >> $GITHUB_ENV
 
  - uses: r-lib/actions/setup-pandoc@v2