Bump gstreamer in Travis

.travis.yml

@@ -23,7 +23,7 @@ matrix:
         - sudo apt-get update -q
         - sudo apt-get install clang-3.9 llvm-3.9-dev llvm-3.9-runtime libunwind8-dev -y
         - pip install virtualenv
-        - curl -L https://servo-deps.s3.amazonaws.com/gstreamer/gstreamer-1.14-x86_64-linux-gnu.20190213.tar.gz | tar xz
+        - curl -L https://servo-deps.s3.amazonaws.com/gstreamer/gstreamer-1.16-x86_64-linux-gnu.20190515.tar.gz | tar xz
         - sed -i "s;prefix=/opt/gst;prefix=$PWD/gst;g" $PWD/gst/lib/pkgconfig/*.pc
         - export PKG_CONFIG_PATH=$PWD/gst/lib/pkgconfig
         - export GST_PLUGIN_SYSTEM_PATH=$PWD/gst/lib/gstreamer-1.0