Update the install package script to use /opt/homebridge/bin/node

Is your feature request related to a problem? Please describe:
Yes, dgreif/ring#1072 - issue due to this project expecting node to be available on the system $PATH but homebridge has isolated/bundled node from the wider system (reasons available here: https://www.reddit.com/r/homebridge/comments/vusfib/homebridge_and_npm_node_locations_on_raspberry_pi/) ... leading to the homebridge-ring plugin failing to install.

Describe the solution you'd like:
Update

ffmpeg-for-homebridge/package.json

Lines 16 to 18 in 184e3c1

    
           "scripts": { 
        
             "install": "node install.js" 
        
           },

to:

  "scripts": {
    "install": "/opt/homebridge/bin/node install.js"
  },

Describe alternatives you've considered:
It's possible to workaround the issue introduced here by updating ~/.homebridge/package.json and running /opt/homebridge/node npm install inside the ~/.homebridge directory.

Additional context:
Can't think of anything else.

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Don't think this works with macOS though?

Node is in the $PATH when running in the Homebridge context.