fix(examples): Add build:examples npm script

This is the last blocker to bumping our generation to the latest
Speakeasy CLI version. 

The latest version of `speakeasy` requires there to be a
`build:examples` script in `examples/package.json`. This is likely a
bug, because during `speakeasy run` it *adds* the `build:examples`
script (along with a number of other changes to
`examples/package.json`).

Author: rwjblue-glean

examples/package.json

@@ -6,7 +6,8 @@
   "main": "main.js",
   "scripts": {
     "script": "tsx",
-    "start": "npm run script -- ./src/example.ts"
+    "start": "npm run script -- ./src/example.ts",
+    "build:examples": "npm i"
   },
   "keywords": [],
   "author": "",