Fixed error:

----------
                 ID: package_duo
           Function: pkg.installed
               Name: duo-unix
             Result: False
            Comment: Problem encountered installing package(s). Additional info follows:
              errors:
                  - E: There were unauthenticated packages and -y was used without --allow-unauthenticated

linux/system/auth/duo.sls

 package_duo:
   pkg.installed:
     - name: duo-unix
+    - skip_verify: True
+
 
 login_duo:
   file.managed: