use jobs to devise emails delivery

Gemfile.lock

@@ -90,6 +90,7 @@ GEM
     choice (0.2.0)
     coderay (1.1.3)
     concurrent-ruby (1.1.9)
+    connection_pool (2.2.5)
     crass (1.0.6)
     datetime_picker_rails (0.0.7)
       momentjs-rails (>= 2.8.1)
@@ -237,6 +238,7 @@ GEM
     rb-fsevent (0.11.0)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
+    redis (4.4.0)
     regexp_parser (2.1.1)
     request_store (1.5.0)
       rack (>= 1.4)
@@ -302,6 +304,10 @@ GEM
     semantic_range (3.0.0)
     shoulda-matchers (5.0.0)
       activesupport (>= 5.2.0)
+    sidekiq (6.2.1)
+      connection_pool (>= 2.2.2)
+      rack (~> 2.0)
+      redis (>= 4.2.0)
     slack-notifier (2.4.0)
     spring (2.1.1)
     sprockets (4.0.2)
@@ -374,6 +380,7 @@ DEPENDENCIES
   rubocop-shopify
   sass-rails (>= 6)
   shoulda-matchers (~> 5.0)
+  sidekiq (~> 6.2)
   slack-notifier
   spring
   tailwindcss-rails