small grammar fix (#437)

## Description:
Removed a comma where it shouldn't be.

Fixes #463 

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [x] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

## Please put your Discord username so you can be contacted if a bug or
regression is found:
N/A

src/client/graphics/layers/EventsDisplay.ts

@@ -282,7 +282,7 @@ export class EventsDisplay extends LitElement implements Layer {
       });
     } else if (betrayed === myPlayer) {
       this.addEvent({
-        description: `${traitor.name()}, broke their alliance with you`,
+        description: `${traitor.name()} broke their alliance with you`,
         type: MessageType.ERROR,
         highlight: true,
         createdAt: this.game.ticks(),