rename fumi-chan_(nhk) -> fuyu-chan

BUR #61114 is pending approval.

rename fumi-chan_(nhk) -> fuyu-chan

This tag seems to be a typo. The character is a personification of winter (冬 fuyu) and her name is 冬ちゃん (fuyu-chan), as seen in the Pixiv link below.

https://dic.pixiv.net/a/冬ちゃん