Update dependency react-testing-library to v6

package.json

@@ -93,7 +93,7 @@
     "jest-dom": "3.1.1",
     "node-fetch": "1.7.3",
     "prettier": "1.16.4",
-    "react-testing-library": "5.8.0",
+    "react-testing-library": "6.0.0",
     "webpack-dev-server": "3.2.0"
   },
   "scripts": {

yarn.lock

@@ -7813,10 +7813,10 @@ react-test-renderer@^16.0.0-0:
     react-is "^16.8.2"
     scheduler "^0.13.2"
 
-react-testing-library@5.8.0:
-  version "5.8.0"
-  resolved "https://registry.yarnpkg.com/react-testing-library/-/react-testing-library-5.8.0.tgz#b5163758b1ddfd2e15c3cd2790562a527a1bb0a5"
-  integrity sha512-cYOX8aUKea5ojFVXkhLbNEAq86nYqBlhKulJI/0v8JfwWyQm+kbyNKFfyci6b2qI4KUEvBYZKWx+zZWeYrYOOA==
+react-testing-library@6.0.0:
+  version "6.0.0"
+  resolved "https://registry.yarnpkg.com/react-testing-library/-/react-testing-library-6.0.0.tgz#81edfcfae8a795525f48685be9bf561df45bb35d"
+  integrity sha512-h0h+YLe4KWptK6HxOMnoNN4ngu3W8isrwDmHjPC5gxc+nOZOCurOvbKVYCvvuAw91jdO7VZSm/5KR7TxKnz0qA==
   dependencies:
     "@babel/runtime" "^7.3.1"
     dom-testing-library "^3.13.1"