Add Podman check to #running_in_container?

This solves the issue of running Selenium tests on Arm Mac (via Podman
Desktop), among other issues.

Author: awilfox

lib/berkeley_library/docker.rb

@@ -7,7 +7,7 @@ module BerkeleyLibrary
   module Docker
     class << self
       def running_in_container?
-        File.exist?('/.dockerenv') || init_cgroup_is_dockerish?
+        File.exist?('/.dockerenv') || init_cgroup_is_dockerish? || env_is_podmanish?
       end
 
       private
@@ -19,6 +19,10 @@ def init_cgroup_is_dockerish?
           false
         end
       end
+
+      def env_is_podmanish?
+        ENV.fetch('container', '') == 'podman'
+      end
     end
   end
 end