fix: Unescape Slack incoming messages (#2604)

spec/lib/integrations/slack/incoming_message_builder_spec.rb

@@ -33,6 +33,7 @@ describe Integrations::Slack::IncomingMessageBuilder do
         allow(builder).to receive(:sender).and_return(nil)
         builder.perform
         expect(conversation.messages.count).to eql(messages_count + 1)
+        expect(conversation.messages.last.content).to eql('this is test https://chatwoot.com Hey @Sojan Test again')
       end
 
       it 'does not create message for invalid event type' do

spec/support/slack_stubs.rb

@@ -46,7 +46,7 @@ module SlackStubs
     {
       "client_msg_id": 'ffc6e64e-6f0c-4a3d-b594-faa6b44e48ab',
       "type": 'message',
-      "text": 'this is test',
+      "text": 'this is test <https://chatwoot.com> Hey <@U019KT237LP|Sojan> Test again',
       "user": 'ULYPAKE5S',
       "ts": '1588623033.006000',
       "team": 'TLST3048H',