Install default fiddle on latest ruby on specs that need it

Otherwise first OS customizations load and activate that fiddle version,
but then when we change to `Gem.default_dir`, that fiddle version is no
longer there.

bundler/spec/commands/clean_spec.rb

@@ -638,7 +638,7 @@ def should_not_have_gems(*gems)
       s.executables = "irb"
     end
 
-    realworld_system_gems "fiddle --version 1.0.6", "tsort --version 0.1.0", "pathname --version 0.1.0", "set --version 1.0.1"
+    realworld_system_gems "fiddle --version 1.0.8", "tsort --version 0.1.0", "pathname --version 0.1.0", "set --version 1.0.1"
 
     install_gemfile <<-G
       source "#{file_uri_for(gem_repo2)}"

bundler/spec/install/gems/standalone_spec.rb

@@ -113,7 +113,7 @@
       skip "does not work on rubygems versions where `--install_dir` doesn't respect --default" unless Gem::Installer.for_spec(loaded_gemspec, :install_dir => "/foo").default_spec_file == "/foo/specifications/default/bundler-#{Bundler::VERSION}.gemspec" # Since rubygems 3.2.0.rc.2
       skip "does not work on old rubies because the realworld gems that need to be installed don't support them" if RUBY_VERSION < "2.7.0"
 
-      realworld_system_gems "fiddle --version 1.0.6", "tsort --version 0.1.0"
+      realworld_system_gems "fiddle --version 1.0.8", "tsort --version 0.1.0"
 
       necessary_system_gems = ["optparse --version 0.1.1", "psych --version 3.3.2", "yaml --version 0.1.1", "logger --version 1.4.3", "etc --version 1.2.0", "stringio --version 3.0.0"]
       necessary_system_gems += ["shellwords --version 0.1.0", "base64 --version 0.1.0", "resolv --version 0.2.1"] if Gem.rubygems_version < Gem::Version.new("3.3.3.a")