Karabiner Elements rule to use KeyChron K8 microphone key with MuteDeck

mutedeck.json

{
    "title": "Keychron K8 Microphone Button to MuteDeck Mute",
    "rules": [
        {
            "description": "Toggle mute via MuteDeck API",
            "manipulators": [
                {
                    "from": {
                        "modifiers": {
                            "mandatory": [
                                "fn"
                            ]
                        },
                        "key_code": "spacebar"
                    },
                    "to": [
                        {
                            "shell_command": "curl --silent -X POST http://localhost:3491/v1/mute",
                            "lazy": true
                        }
                    ],
                    "type": "basic"
                }
            ]
        }
    ]
}