Drop unused Rake task (#564)

Rakefile

@@ -9,12 +9,11 @@ require "fileutils"
 require "overcommit"
 
 RuboCop::RakeTask.new
-RSpec::Core::RakeTask.new(:rspec)
+RSpec::Core::RakeTask.new
 
 desc "When releasing the gem, re-fetch latest cacert.pem from curl.haxx.se. Developer task."
 task :update_ssl_ca_file do
   `pushd lib/github_changelog_generator/ssl_certs && curl --remote-name --time-cond cacert.pem https://curl.haxx.se/ca/cacert.pem && popd`
 end
 
-task checks: %i[rubocop rspec]
-task default: %i[rubocop rspec]
+task default: %i[rubocop spec]