Add Extension key to composer.json

[gregordonsky]

Extension key in composer.json is missing.

For example:

{
    "name": "pluswerk/elasticsearch",
    "type": "typo3-cms-extension",
    "description": "Pluswerk: Elasticsearch adapter for TYPO3 - Modificato By Mediaus",
    "homepage": "https://www.pluswerk.ag",
    "license": "GPL-2.0-or-later",
    "support": {
        "source": "https://www.pluswerk.ag"
    },
    "autoload": {
        "psr-4": {
            "Pluswerk\\Elasticsearch\\": "Classes/"
        }
    },
    "require": {
        "typo3/cms-core": ">=9.5",
        "elasticsearch/elasticsearch": "^7.10"
    },
    "extra": {
        "typo3/cms": {
            "extension-key": "elasticsearch"
        }
    }
}