[rubygems/rubygems] Delay pending spec

We had actually cancelled this change. After a second look though, it
does seem like a reasonable plan since `bundle list` makes more sense
for listing gems, and `bundle info` makes more sense for showing info
about a particular gem. `bundle show` is a strange mix of both.

Let's schedule this for Bundler 5.

ruby/rubygems@7071a1e82e

Author: deivid-rodriguez

spec/bundler/commands/show_spec.rb

@@ -239,6 +239,6 @@
   end
 end
 
-RSpec.describe "bundle show", bundler: "4" do
+RSpec.describe "bundle show", bundler: "5" do
   pending "shows a friendly error about the command removal"
 end