Use PORT env var to customize script/develop port

[pzich]

This allows the port used by script/develop to be customized by setting the PORT env var, e.g:

> PORT=5432 ./script/develop

   ┌────────────────────────────────────────┐
   │                                        │
   │   Serving!                             │
   │                                        │
   │   - Local:    http://localhost:5432    │
   │   - Network:  http://10.0.0.10:5432    │
   │                                        │
   │   Copied local address to clipboard!   │
   │                                        │
   └────────────────────────────────────────┘

Otherwise defaults to the current 5001

[balloob]

Thanks