fix(package): update @tensorflow/tfjs-converter to version 1.7.1

Closes #27

Author: greenkeeper[bot]

package.json

@@ -27,7 +27,7 @@
   },
   "dependencies": {
     "@tensorflow-models/coco-ssd": "2.0.1",
-    "@tensorflow/tfjs-converter": "1.4.0",
+    "@tensorflow/tfjs-converter": "1.7.1",
     "@tensorflow/tfjs-core": "1.4.0",
     "react": "16.13.1",
     "react-dom": "16.13.1"