TypeScript update to 6.0.3 (#3806)

## Description:

Updating TypeScript to 6.0.3.
Updating TypeScript-eslint to 8.59.1 for TS6 support.
Concurrently needed to get updated as well to remove deprecated warning.

Most things deleted are now just defaults.

## Please complete the following:

- [X] I have added screenshots for all UI updates
- [X] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [X] I have added relevant tests to the test directory
- [X] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

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

Babyboucher

src/client/Matchmaking.ts

@@ -123,7 +123,7 @@ export class MatchmakingModal extends BaseModal {
         this.gameCheckInterval = setInterval(() => this.checkGame(), 1000);
       }
     };
-    this.socket.onerror = (event: ErrorEvent) => {
+    this.socket.onerror = (event: Event) => {
       console.error("WebSocket error occurred:", event);
     };
     this.socket.onclose = () => {