update metro to 0.47.1 to fix sourcemaps in plugins

Summary: Inline sourcemaps were broken in Metro until 0.47.1, so now we can debug flipper plugins again!

Reviewed By: passy

Differential Revision: D10200221

fbshipit-source-id: 919c1bc4f7aee720f25f2375ffbd8a786ebd0017

static/compilePlugins.js

@@ -173,9 +173,6 @@ async function compilePlugin(
           out,
           dev: false,
           sourceMap: true,
-          // due to a bug in metro inline source maps are only created when
-          // sourceMapUrl is truthy: https://github.com/facebook/metro/pull/260
-          sourceMapUrl: 'inline',
         },
       );
     } catch (e) {