Bug 1495968 [wpt PR 13322] - Update wpt metadata, a=testonly

wpt-pr: 13322
wpt-type: metadata

testing/web-platform/meta/webrtc/RTCRtpParameters-encodings.html.ini

@@ -95,3 +95,6 @@
   [setParameters() with modified encoding.maxFramerate should succeed without RTCRtpTransceiverInit]
     expected: FAIL
 
+  [sender.setParameters() with encodings unset should reject with TypeError]
+    expected: FAIL
+