Test without pak config

Author: glin

.github/workflows/build.yaml

@@ -39,9 +39,8 @@ jobs:
       - name: Temporarily configure pak to use manylinux_2_28
         if: startsWith(matrix.config.os, 'ubuntu') && matrix.config.r != 'devel'
         run: |
+          # Override actions PPM repo and do not autodetect the distro
           echo "RSPM=https://p3m.dev/cran/__linux__/manylinux_2_28/latest" >> $GITHUB_ENV
-          # Override pak's CRAN mirror and do not autodetect the distro
-          echo "PKG_CRAN_MIRROR=https://p3m.dev/cran/__linux__/manylinux_2_28/latest" >> $GITHUB_ENV
           # Disable automatic system requirements installation since it is unnecessary
           echo "PKG_SYSREQS=FALSE" >> $GITHUB_ENV