Upgrade svgr to 4.0.3

Author: alaycock

packages/react-scripts/package.json

@@ -25,7 +25,7 @@
   "types": "./lib/react-app.d.ts",
   "dependencies": {
     "@babel/core": "7.1.0",
-    "@svgr/webpack": "2.4.1",
+    "@svgr/webpack": "4.0.3",
     "babel-core": "7.0.0-bridge.0",
     "babel-eslint": "9.0.0",
     "babel-jest": "23.6.0",