Add framed and mathtools

Author: kolesarm

.github/workflows/rhub.yaml

@@ -85,6 +85,7 @@ jobs:
             xcolor
             fancyvrb
             framed
+            mathtools
       - uses: r-lib/actions/setup-pandoc@v2
       ## MK: END modification
       - uses: r-hub/actions/checkout@v1