Punctuation breaks user mention

Description:

When tagging someone in a chat message within a public channel, if you include punctuation after the tag it breaks the tagging functionality.

Steps to reproduce:

1. Message in a public channel while tagging a user in the channel.
2. Include a period or other punctuation after the user tag.
3. The tag is not active when sent to the channel

Expected behavior:

A tag should remain active even in the case when punctuation is included after it.

Actual behavior:

Server Setup Information:

I'm just a lowly user of this server, so I'm not totally sure. The version where unread channels start appearing at the top of the channels list

• Version of Rocket.Chat Server:
• Operating System:
• Deployment Method: docker
• Number of Running Instances: 2 (prod/test)
• DB Replicaset Oplog:
• NodeJS Version:
• MongoDB Version:

Client Setup Information

• Desktop App or Browser Version: Desktop, but it's on both.
• Operating System: Mac

Reproduce the issue by tagging a user in a public-channel chat message and placing punctuation immediately after the tag, using both the desktop app and browser if possible. Trace the message mention handling from the chat composer or message rendering entry point; done means the tag remains active when followed by punctuation, with coverage for the reported punctuation cases.