Fix call.collectCallStats() (#2480)

Regressed by #2352
(you can just use RTCStatsReport as an iterator directly (which
was was what that code was doing before) which uses entries(
which gives you key/value pairs, but using forEach gives you just
the value.

Author: dbkr

src/webrtc/call.ts

@@ -708,9 +708,9 @@ export class MatrixCall extends TypedEventEmitter<CallEvent, CallEventHandlerMap
 
         const statsReport = await this.peerConn.getStats();
         const stats = [];
-        statsReport.forEach(item => {
-            stats.push(item[1]);
-        });
+        for (const item of statsReport.values()) {
+            stats.push(item);
+        }
 
         return stats;
     }