Update React dependencies

So we can test componentWillReceiveProps changes

Author: fongandrew

package-lock.json

@@ -83,10 +83,10 @@
     "node-sass": "4.12.0",
     "prismjs": "1.16.0",
     "raf": "3.4.1",
-    "react": "16.8.6",
-    "react-dom": "16.8.6",
+    "react": "16.12.0",
+    "react-dom": "16.12.0",
     "react-redux": "7.0.3",
-    "react-test-renderer": "16.8.6",
+    "react-test-renderer": "16.12.0",
     "redux": "4.0.1",
     "rimraf": "2.6.3",
     "sass-loader": "7.1.0",