Do not show_diff in freeradius::cert.

This can lead to private keys being exposed in logs when Puppet runs.

manifests/cert.pp

@@ -23,6 +23,7 @@ define freeradius::cert (
     group     => $fr_group,
     source    => $source,
     content   => $content,
+    show_diff => false,
     require   => [File["${fr_basepath}/certs"], Package[$fr_package], Group[$fr_group]],
     notify    => Service[$fr_service],
   }