Updated using the new item state feature to depend on daylight as a clock would. Asleep during the day and awake during the night, the axolotl is nocturnal. The animated transition remains, but is dependent on daytime instead of being an animated texture. Designed to only work in the overworld so that your axolotl buddy can always support you during your end adventures, and added a new nether texture where the water is almost dried up.
Upon request, added an animated texture that cycles through the sleepy texture and one more outside the bucket based on concept art.
Initial release with static texture. Axolotl permanently sleeps while in the bucket.