Apply suggestion from @Andriamanitra

Co-authored-by: Mikko <Andriamanitra@users.noreply.github.com>

Author: injust

runtime/syntax/ruby.yaml

@@ -1,7 +1,7 @@
 filetype: ruby
 
 detect:
-    filename: '\.(rb|rake|gemspec)$|^(.*[\\/])?(Gemfile|config.ru|Rakefile|Capfile|Vagrantfile|Guardfile|Appfile|Fastfile|Pluginfile|Podfile|\.?[Bb]rewfile)$'
+    filename: '\.(rb|rake|gemspec)$|^(.*[\\/])?(Gemfile|config\.ru|Rakefile|Capfile|Vagrantfile|Guardfile|Appfile|Fastfile|Pluginfile|Podfile|\.?[Bb]rewfile)$'
     header: "^#!.*/(env +)?ruby( |$)"
 
 rules: