fix(deps): update dependency botbuilder to v4.21.4

Author: renovate[bot]

package.json

@@ -40,7 +40,7 @@
     "tap": "16.3.2"
   },
   "dependencies": {
-    "botbuilder": "4.16.0",
+    "botbuilder": "4.21.4",
     "brreg": "5.0.6",
     "fortune-cookie": "0.0.1",
     "got": "12.1.0",