chore: Upgrade rails and ruby versions (#2400)

ruby version: 3.0.2
rails version: 6.1.4

spec/factories/integrations/hooks.rb

@@ -3,7 +3,7 @@ FactoryBot.define do
     app_id { 'slack' }
     inbox
     account
-    settings { { 'test': 'test' } }
+    settings { { test: 'test' } }
     status { Integrations::Hook.statuses['enabled'] }
     access_token { SecureRandom.hex }
     reference_id { SecureRandom.hex }