create implication gumroad_reward -> paid_reward
Gumroad reward is a subset of paid reward.
P.S. I went and fixed the 17 pages of posts that were gumroad rewards tagged with patreon reward, so gumroad reward should be properly populated now.
EDIT: This tag implication is pending automatic rejection in 5 days.
EDIT: The tag implication gumroad_reward -> paid_reward (forum #150459) has been approved by @Hillside_Moose.
Updated by DanbooruBot