Apply a fix/patch after deploying & running composer.

composer.json

{
    // . . .
    "scripts": {
        "post-install-cmd": [
            // NOTE: cwd is the location of the composer.json
            // -t/--batch (supress interactivity)
            "patch -t -p0 < path/to/file.patch"
        ]
    }
    // . . .
}