fix stupid express thing

src/api/routes/channels/#channel_id/threads.ts

@@ -49,7 +49,7 @@ router.post(
     }),
     async (req: Request, res: Response) => {
         // TODO: check for differences with https://github.com/spacebarchat/server/pull/876/files#diff-95be9c4cdfd8ba6f67361cd40b9abc8226b35d83e2bb44bf5b4682f1d66155e9
-        const { channel_id } = req.params;
+        const { channel_id } = req.params as { channel_id: string };
         const body = req.body as ThreadCreationSchema;
 
         const channel = await Channel.findOneOrFail({