[Fix #9593] Fix an error when processing a directory is named {}

Fixes #9593.

This PR fixes the following error when processing a directory is named `{}`.

```console
% mkdir {}
% rubocop
(snip)

File name too long - /tmp//////////////////////////////////////////////...
```

changelog/fix_an_error_when_processing_dir_is_named_empty_braces.md

@@ -0,0 +1 @@
+* [#9593](https://github.com/rubocop/rubocop/issues/9593): Fix an error when processing a directory is named `{}`. ([@koic][])

lib/rubocop/target_finder.rb

@@ -96,6 +96,7 @@ def find_files(base_dir, flags)
     end
 
     def wanted_dir_patterns(base_dir, exclude_pattern, flags)
+      base_dir = base_dir.gsub('/{}/', '/\{}/')
       dirs = Dir.glob(File.join(base_dir.gsub('/**/', '/\**/'), '*/'), flags)
                 .reject do |dir|
                   dir.end_with?('/./', '/../') || File.fnmatch?(exclude_pattern, dir, flags)

spec/rubocop/target_finder_spec.rb

@@ -441,6 +441,19 @@
       expect(found_basenames).to include('ruby4.rb')
     end
 
+    it 'works also if a folder is named "{}"' do
+      create_empty_file('{}/ruby4.rb')
+
+      config = instance_double(RuboCop::Config)
+      exclude_property = { 'Exclude' => [File.expand_path('dir1/**/*')] }
+      allow(config).to receive(:for_all_cops).and_return(exclude_property)
+      allow(config_store).to receive(:for).and_return(config)
+
+      expect(found_basenames).not_to include('ruby1.rb')
+      expect(found_basenames).to include('ruby3.rb')
+      expect(found_basenames).to include('ruby4.rb')
+    end
+
     # Cannot create a directory with containing `*` character on Windows.
     # https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file#naming-conventions
     unless RuboCop::Platform.windows?