fix: parameter to _onPeerDisconnected

`_onPeerDisconnected` is expecting a `PeerInfo` but it was being passed a pubsub `Peer`.

I'm not sure if this is the correct fix but it resolves this error for me:

```
(node:77189) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'toB58String' of undefined
    at GossipSub._onPeerDisconnected (/Users/alan/Code/pl/ipfs/js-ipfs/node_modules/libp2p-pubsub/src/index.js:190:34)
    at GossipSub._processMessages (/Users/alan/Code/pl/ipfs/js-ipfs/node_modules/libp2p-gossipsub/src/pubsub.js:120:12)
    at runMicrotasks (<anonymous>)
    at processTicksAndRejections (internal/process/task_queues.js:94:5)
```

Author: Alan Shaw

src/pubsub.js

@@ -98,7 +98,7 @@ class BasicPubSub extends Pubsub {
    * @override
    * @param {string} idB58Str peer id string in base58
    * @param {Connection} conn connection
-   * @param {PeerInfo} peer peer info
+   * @param {Peer} peer PubSub peer
    * @returns {void}
    *
    */
@@ -117,7 +117,7 @@ class BasicPubSub extends Pubsub {
         }
       )
     } catch (err) {
-      this._onPeerDisconnected(peer, err)
+      this._onPeerDisconnected(peer.info, err)
     }
   }