Proposal : Update Anime Rifle Is Beautiful: Zenkoku Taikai Is Mokuzen source

Proposal details

This proposal will make the following change(s):

Update the source of the anime Rifle Is Beautiful: Zenkoku Taikai Is Mokuzen

Change the source from Unknown to 4-koma manga

Based on the following reason: Missing

With the source: https://myanimelist.net/anime/40769/Rifle_Is_Beautiful__Zenkoku_Taikai_Is_Mokuzen?q=Rifle%20Is%20Beautiful%3A%20Zenkoku%20Taikai%20Is%20Mokuzen&cat=anime