[rubygems/rubygems] Make sure `bundle viz` specs are actually run

These are marked as realworld, but the realworld workflow file does not
install graphviz, so the specs are actually skipped.

These are not actually realworld, so remove that tag. Now they'll be run
together with the reset of specs in the standard workflow file, which
does install `graphviz`.

https://github.com/rubygems/rubygems/commit/e865fcaa22

spec/bundler/commands/viz_spec.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-RSpec.describe "bundle viz", bundler: "< 3", if: Bundler.which("dot"), realworld: true do
+RSpec.describe "bundle viz", bundler: "< 3", if: Bundler.which("dot") do
   before do
     realworld_system_gems "ruby-graphviz --version 1.2.5"
   end