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

scripts/build-release.js

@@ -156,9 +156,6 @@ function compile(buildFolder) {
       minify: false,
       resetCache: true,
       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',
       entry: path.join(__dirname, '..', 'src', 'init.js'),
       out: path.join(buildFolder, 'bundle.js'),
     },