Slack -> Discord Deleting message with an image does not work.

[noisymime]

Describe the bug
A message created in Slack is bridged through to Discord OK. Deleting that message in Slack will delete the msg in Discord, however not when the original message contains an image.

To Reproduce

• Send a message in Slack that contains an image
• Confirm msg and image appear in Discord
• Delete msg in Slack
• Msg is not deleted in Discord

Expected behavior
Messages containing images should be deleted, just like messages containing no images.

Screenshots/debug logs
Debug log when deleting a message containing an image.

[0235] DEBUG slack:        [handleSlackClient:bridge/slack/handlers.go:52] == Receiving event &slack.MessageEvent{Msg:slack.Msg{ClientMsgID:"", Type:"message", Channel:"C09MSS9U1", User:"", Text:"", Timestamp:"1643760897.164700", ThreadTimestamp:"", IsStarred:false, PinnedTo:[]string(nil), Attachments:[]slack.Attachment(nil), Edited:(*slack.Edited)(nil), LastRead:"", Subscribed:false, UnreadCount:0, SubType:"message_deleted", Hidden:true, DeletedTimestamp:"1643760888.862179", EventTimestamp:"1643760897.164700", BotID:"", Username:"", Icons:(*slack.Icon)(nil), BotProfile:(*slack.BotProfile)(nil), Inviter:"", Topic:"", Purpose:"", Name:"", OldName:"", Members:[]string(nil), ReplyCount:0, Replies:[]slack.Reply(nil), ParentUserId:"", Files:[]slack.File(nil), Upload:false, Comment:(*slack.Comment)(nil), ItemType:"", ReplyTo:0, Team:"", Reactions:[]slack.ItemReaction(nil), ResponseType:"", ReplaceOriginal:false, DeleteOriginal:false, Blocks:slack.Blocks{BlockSet:[]slack.Block(nil)}}, SubMessage:(*slack.Msg)(nil), PreviousMessage:(*slack.Msg)(0xc00026f680)}
[0235] DEBUG slack:        [handleSlack:bridge/slack/handlers.go:44] <= Message is &config.Message{Text:"msg_delete", Channel:"general", Username:"", UserID:"", Avatar:"", Account:"slack.speeduino", Event:"msg_delete", Protocol:"slack", Gateway:"", ParentID:"", Timestamp:time.Date(1, time.January, 1, 0, 0, 0, 0, time.UTC), ID:"1643760888.862179", Extra:map[string][]interface {}{}}
[0235] DEBUG gateway:      [SendMessage:gateway/gateway.go:479] => Sending config.Message{Text:"msg_delete", Channel:"general", Username:"", UserID:"", Avatar:"", Account:"slack.speeduino", Event:"msg_delete", Protocol:"slack", Gateway:"gateway_main", ParentID:"", Timestamp:time.Date(2022, time.February, 2, 0, 14, 57, 982287616, time.Local), ID:"1643760888.862179", Extra:map[string][]interface {}{}} from slack.speeduino (general) to discord.speeduino (general)
[0235] DEBUG discord:      [Send:bridge/discord/discord.go:235] => Receiving config.Message{Text:"msg_delete", Channel:"general", Username:" (Slack)", UserID:"", Avatar:"", Account:"slack.speeduino", Event:"msg_delete", Protocol:"slack", Gateway:"gateway_main", ParentID:"", Timestamp:time.Date(2022, time.February, 2, 0, 14, 57, 982287616, time.Local), ID:"", Extra:map[string][]interface {}{}}

One thing I've noted is that on the final line there is ID:"". When performing a deletion on a message that does not contain an image, this ID value contains the msg ID, however this appears to be missing when the original msg contains an image.

Environment (please complete the following information):

• OS: linux (Docker image)
• Matterbridge version: 1.23.2 73ec02a

Additional context
Config:

[discord]
[discord.speeduino]
Token="XXXX"

# Server (REQUIRED) is the ID or name of the guild to connect to, selected from the guilds the bot has been invited to
Server="Speeduino"
AutoWebhooks=true
RemoteNickFormat="{NICK} (Slack)"
PreserveThreading=true

[slack]
[slack.speeduino]
Token="XXXX"
RemoteNickFormat="{NICK} (Discord)"
PreserveThreading=true

[[gateway]]
name="gateway_main"
enable=true

[[gateway.inout]]
account="discord.speeduino"
channel="general"

[[gateway.inout]]
account="slack.speeduino"
channel="general"

[[samechannelgateway]]
   name="samechannel"
   enable = true
   accounts = [ "discord.speeduino","slack.speeduino" ]
   channels = [ "git","development","hardware","help","random","simulators","theory","yourprojects","wiki"]