Update rubocop-rspec to version 3.10.2

Author: depfu[bot]

image_optim.gemspec

@@ -47,6 +47,6 @@ EOF
   s.add_development_dependency 'rspec', '~> 3.0'
   if RUBY_VERSION >= '2.5' && !Gem.win_platform? && !defined?(JRUBY_VERSION)
     s.add_development_dependency 'rubocop', '~> 1.22', '!= 1.22.2'
-    s.add_development_dependency 'rubocop-rspec', '~> 2.0'
+    s.add_development_dependency 'rubocop-rspec', '~> 3.10'
   end
 end