small rubocop fix

Author: Jef Spaleta

sensu-plugins-postgres.gemspec

@@ -34,7 +34,7 @@ Gem::Specification.new do |s| # rubocop:disable Metrics/BlockLength
   s.test_files             = s.files.grep(%r{^(test|spec|features)/})
   s.version                = SensuPluginsPostgres::Version::VER_STRING
 
-  s.add_runtime_dependency 'sensu-plugin', '~> 4.0' 
+  s.add_runtime_dependency 'sensu-plugin', '~> 4.0'
 
   s.add_runtime_dependency 'dentaku',      '3.3.4'
   s.add_runtime_dependency 'pg',           '1.2.1'