Upgrade axios to 0.19.0 (#86)

Author: draffensperger

examples/user_interaction/server/package-lock.json

@@ -24,11 +24,11 @@
     "@opencensus/exporter-zipkin": "^0.0.12",
     "@opencensus/nodejs": "^0.0.12",
     "@opencensus/propagation-tracecontext": "^0.0.12",
-    "axios": "^0.18.0",
+    "axios": "^0.19.0",
     "http": "*",
     "sleep": "^6.1.0"
   },
   "devDependencies": {
     "semistandard": "^13.0.1"
   }
-}
+}