Fix the mattermost created at timestamp

app/models/pager_tree/integrations/channel/mattermost/v3.rb

@@ -2,5 +2,9 @@ module PagerTree::Integrations
   class Channel::Mattermost::V3 < Channel::Slack::V3
     # we can just piggy back the Channel::Slack::V3 since Mattermost is a clone of Slack
     # both integrations have the same exact functionality
+
+    def _alert_created_at_timestamp_formatted
+      _alert.created_at.utc.iso8601.to_s
+    end
   end
 end

app/models/pager_tree/integrations/channel/slack/v3.rb

@@ -68,6 +68,10 @@ def adapter_process_outgoing
       outgoing_webhook_delivery
     end
 
+    def _alert_created_at_timestamp_formatted
+      "<!date^#{_alert.created_at.utc.to_i}^{date_num} {time_secs}|#{_alert.created_at.utc.to_i}>"
+    end
+
     private
 
     def _alert
@@ -99,7 +103,7 @@ def _blocks
               },
               {
                 title: "Created",
-                value: "<!date^#{_alert.created_at.utc.to_i}^{date_num} {time_secs}|#{_alert.created_at.utc.to_i}>",
+                value: _alert_created_at_timestamp_formatted,
                 short: "true"
               },
               {

test/models/pager_tree/integrations/channel/mattermost/v3_test.rb

@@ -83,7 +83,7 @@ class Channel::Mattermost::V3Test < ActiveSupport::TestCase
               },
               {
                 title: "Created",
-                value: "<!date^#{@alert.created_at.utc.to_i}^{date_num} {time_secs}|#{@alert.created_at.utc.to_i}>",
+                value: @alert.created_at.utc.iso8601.to_s,
                 short: "true"
               },
               {