Ignore links to arc.umich.edu.

Author: joaander

.github/workflows/test.yaml

@@ -126,6 +126,7 @@ jobs:
       with:
         args: -n
               --exclude https://glotzerlab.engin.umich.edu
+              --exclude https://arc.umich.edu
               --exclude 'https://github.com/glotzerlab/row/edit.*'
               --exclude doi.org
               './**/*.md'