[core] update mapbox-gl-js submodule pin

* disables transition render test (transitions are not supported with Still image rendering in Node.js)
* removes support for hillshade-illumniation-direction-transition

scripts/generate-shaders.js

@@ -7,8 +7,6 @@ const outputPath = 'src/mbgl/shaders';
 
 var shaders = require('../mapbox-gl-js/src/shaders');
 
-delete shaders.hillshade;
-delete shaders.hillshadePrepare;
 delete shaders.heatmap;
 delete shaders.heatmapTexture;