in macOS, install JPEG

Author: Accio

.github/workflows/standard-ci-workflow.yml

@@ -41,6 +41,10 @@ jobs:
           use-public-rspm: true
           extra-repositories: https://bedapub.r-universe.dev
 
+      - name: Install system dependencies (macOS)
+        if: runner.os == 'macOS'
+        run: brew install jpeg
+
       - uses: r-lib/actions/setup-r-dependencies@v2
         with:
           extra-packages: any::rcmdcheck, any::testthat, any::Vennerable, any::ribiosArg