* add enabling smtp env variable

* fix typo

* Add missing environment variable for enabling smtp

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Co-authored-by: Goeran Poehner <goeran.poehner@gmail.com>

Normally I'd wait until you release a new version. This time however only the `amd64` image of RabbitMQ was pushed: https://hub.docker.com/layers/library/rabbitmq/3.13.5/images/sha256-c534306ad054bd05914bb218ee7b53cf8a5e6cb7d8d085ce5a349cff39982998?context=explore
3.13.6 doesn't have this issue and also pusses the `arm64` image alongside all the usual support platforms: https://hub.docker.com/layers/library/rabbitmq/3.13.6/images/sha256-02768f2e915808a8d6167b5aed372e881930108cac0b4a585c47e08f740b4c5e?context=explore