add script to set process concurrency on start/restart/run from config

script/update_process_concurrency.rb

@@ -0,0 +1,16 @@
+#!/usr/bin/env ruby
+
+require File.expand_path('../../lib/postal/config', __FILE__)
+worker_quantity = Postal.config.workers&.quantity || 1
+hash = {
+  'processes' => {
+    'worker' => {
+      'quantity' => worker_quantity
+    },
+    'fast' => {
+      'quantity' => Postal.config.fast_server ? 1 : 0
+    }
+  }
+}.to_yaml
+
+File.open(Postal.app_root.join('Procfile.local'), 'w') { |f| f.write(hash + "\n")}