Add parallel to gemspec

Gemfile.lock

@@ -10,6 +10,7 @@ PATH
   specs:
     tapioca (0.7.0)
       bundler (>= 1.17.3)
+      parallel (>= 1.21.0)
       pry (>= 0.12.2)
       rbi (~> 0.0.0, >= 0.0.14)
       sorbet-static-and-runtime (>= 0.5.9204)

lib/tapioca/executor.rb

@@ -20,10 +20,6 @@ def initialize(queue, number_of_workers: nil)
         number_of_workers || [Etc.nprocessors, (queue.length.to_f / MINIMUM_ITEMS_PER_WORKER).ceil].min,
         Integer
       )
-
-      # The number of items that will be processed per worker, so that we can split the queue into groups and assign
-      # them to each one of the workers
-      @items_per_worker = T.let((queue.length.to_f / @number_of_workers).ceil, Integer)
     end
 
     sig do

tapioca.gemspec

@@ -24,6 +24,7 @@ Gem::Specification.new do |spec|
   spec.metadata["allowed_push_host"] = "https://rubygems.org"
 
   spec.add_dependency("bundler", ">= 1.17.3")
+  spec.add_dependency("parallel", ">= 1.21.0")
   spec.add_dependency("pry", ">= 0.12.2")
   spec.add_dependency("rbi", "~> 0.0.0", ">= 0.0.14")
   spec.add_dependency("sorbet-static-and-runtime", ">= 0.5.9204")