Update de.json to fix wrong German translations of moon phases

This addresses [[Bug] Wrong German translations for the moon phases](https://github.com/ngocjohn/lunar-phase/issues/9#top) fixing the wrong German translations for the occurrences of "first_quarter" and "last_quarter". Makes it consistent with the same changes to the lunar-phase-card in https://github.com/ngocjohn/lunar-phase-card/pull/43