fix: fix broadcasting (#361)

`except` is undefined when using the namespace to broadcast.

This should fix the following error in the latest release:

```
TypeError: opts.except is not iterable
  at RedisAdapter.broadcast (.../node_modules/socket.io-redis/dist/index.js:255:34)
  at Namespace.emit (.../node_modules/socket.io/dist/namespace.js:175:22)
  at Server.<computed> [as emit] (.../node_modules/socket.io/dist/index.js:442:33)
```

lib/index.ts

@@ -346,7 +346,7 @@ export class RedisAdapter extends Adapter {
     if (!onlyLocal) {
       const rawOpts = {
         rooms: [...opts.rooms],
-        except: [...opts.except],
+        except: [...new Set(opts.except)],
         flags: opts.flags,
       };
       const msg = msgpack.encode([this.uid, packet, rawOpts]);

test/index.js

@@ -65,6 +65,26 @@ let socket1, socket2, socket3;
       });
     });
 
+    it("uses a namespace to broadcast to rooms", () => {
+      socket1.join("woot");
+      client2.emit("do broadcast");
+      socket2.on("do broadcast", () => {
+        namespace2.to("woot").emit("broadcast");
+      });
+
+      client1.on("broadcast", () => {
+        setTimeout(done, 100);
+      });
+
+      client2.on("broadcast", () => {
+        throw new Error("Not in room");
+      });
+
+      client3.on("broadcast", () => {
+        throw new Error("Not in room");
+      });
+    });
+
     it("broadcasts to multiple rooms at a time", (done) => {
       function test() {
         client2.emit("do broadcast");