Missing required lib `react/child-process` for local binary support

[sukhwinder33445]

Describe the bug

Class HeadlessChrome is missing the class React\ChildProcess\Process.

Additional context

Add package react/child-process once support for php85 is available.

[sukhwinder33445]

Note for myself: To use/test linked branch (temporarily) as library:
1 .add the following to composer.json file

"repositories": [
    {
      "type": "vcs",
      "url": "https://github.com/6b7562617765726c6f73/child-process"
    }
  ]

2. Execute composer require react/child-process:dev-php85