Add type:boolean to workflow_dispatch in README.md

[nickbenedetti]

The workflow_dispatch is missing the type to know what should be in the prompt. Currently:

Expected:

Fix: update the README.md to include type:boolean so it reads:

on:
  workflow_dispatch:
    inputs:
      debug_enabled:
        description: 'Run the build with tmate debugging enabled (https://github.com/marketplace/actions/debugging-with-tmate)'
        type: boolean
        required: false
        default: false