Declare Lumo as a dependency

This means that we always have the right version, regardless of what's
in the global environment. Note that npm scripts (including `npm
start`) automatically prepend `./node_modules/.bin` to $PATH, which is
how this works.

See also http://module.party

package.json

@@ -4,7 +4,11 @@
   "repository": "https://github.com/yogthos/mastodon-bot",
   "license": "MIT",
   "dependencies": {
+    "lumo-cljs": "^1.8.0",
     "mastodon-api": "1.3.0",
     "twitter": "1.7.1"
+  },
+  "scripts": {
+    "start": "./mastodon-bot.cljs"
   }
 }