Bump gstreamer-uwp msvc-package to 1.16.0.5

This new package contains a hacky gstreamer-webrtc-1.0.pc file so that we can still do self-contained builds without relying on external PKG_CONFIG_PATH.

python/servo/packages.py

@@ -9,6 +9,6 @@
     "ninja": "1.7.1",
     "nuget": "08-08-2019",
     "openssl": "111.3.0+1.1.1c-vs2017",
-    "gstreamer-uwp": "1.16.0.4",
+    "gstreamer-uwp": "1.16.0.5",
     "openxr-loader-uwp": "1.0",
 }