add support for ubuntu20.04

Signed-off-by: Martin Schurz <Martin.Schurz@t-systems.com>

Author: schurzi

libraries/ssh_crypto.rb

@@ -210,7 +210,7 @@ def valid_privseparation # rubocop:disable Metrics/CyclomaticComplexity
       end
     when 'ubuntu'
       case inspec.os[:release]
-      when /^18\./
+      when /^18\./, /^20\./
         ps = ps75
       end
     when 'fedora', 'alpine', 'arch'