remove extra whitespace

Author: GrantBirki

rubocop-github.gemspec

@@ -6,7 +6,7 @@ Gem::Specification.new do |s|
   s.name = "rubocop-github"
   s.version = VERSION
   s.summary = "RuboCop GitHub"
-  s.description = "Code style checking for GitHub Ruby repositories "
+  s.description = "Code style checking for GitHub Ruby repositories"
   s.homepage = "https://github.com/github/rubocop-github"
   s.license = "MIT"