fix: avoid running dev-only npm scripts when installing this package

The `install` script is also executed when consumers install Heimdall as a dependency, ie. `npm i @strv/heimdall`. Using `prepare` script we only ever run those commands when someone runs `npm install` while working directly on Heimdall.

package.json

@@ -46,6 +46,6 @@
     "url": "[email protected]:strvcom/heimdall.git"
   },
   "scripts": {
-    "install": "touch node_modules && make"
+    "prepare": "touch node_modules && make"
   }
 }