fix(deps): update dependency downshift to v8

Author: renovate[bot]

packages/combobox/package.json

@@ -23,7 +23,7 @@
     "@babel/runtime": "^7.8.4",
     "@zendeskgarden/container-field": "^3.0.7",
     "@zendeskgarden/container-utilities": "^1.0.8",
-    "downshift": "^7.6.0"
+    "downshift": "^8.0.0"
   },
   "peerDependencies": {
     "prop-types": "^15.6.1",