Update dependency enzyme-adapter-react-16 to v1.15.6

Author: renovate-bot

package.json

@@ -95,7 +95,7 @@
     "cross-env": "5.2.1",
     "doctoc": "1.4.0",
     "enzyme": "3.11.0",
-    "enzyme-adapter-react-16": "1.15.2",
+    "enzyme-adapter-react-16": "1.15.6",
     "enzyme-to-json": "3.4.4",
     "eslint-config-prettier": "6.5.0",
     "eslint-plugin-react": "7.19.0",