fix: pin @types/react-dom to 16.8.5

Author: greenkeeper[bot]

package.json

@@ -23,7 +23,7 @@
   "devDependencies": {
     "@types/jest": "^24.0.13",
     "@types/lodash": "^4.14.133",
-    "@types/react-dom": "^16.8.4",
+    "@types/react-dom": "16.8.5",
     "@types/react-test-renderer": "^16.8.1",
     "@types/sinon": "^7.0.12",
     "@types/sinon-chai": "^3.2.2",