Update MockRTC for fixes and node-datachannel v0.4 (with M1 prebuilds)

Author: pimterry

package-lock.json

@@ -67,7 +67,7 @@
     "lookpath": "^1.2.1",
     "mime-types": "^2.1.27",
     "mobx": "^6.3.5",
-    "mockrtc": "^0.3.0",
+    "mockrtc": "^0.3.1",
     "mockttp": "^3.6.2",
     "node-abort-controller": "^3.0.1",
     "node-fetch": "^2.6.1",