Update TypeScript in integration tests (#498)

Author: merlinnot

integration_test/package.node10.json

@@ -14,10 +14,10 @@
   },
   "main": "lib/index.js",
   "devDependencies": {
-    "typescript": "~3.1.0"
+    "typescript": "~3.5.0"
   },
   "engines": {
     "node": "10"
   },
   "private": true
-}
+}

integration_test/package.node8.json

@@ -14,10 +14,10 @@
   },
   "main": "lib/index.js",
   "devDependencies": {
-    "typescript": "~3.1.0"
+    "typescript": "~3.5.0"
   },
   "engines": {
     "node": "8"
   },
   "private": true
-}
+}