+1 putting it in 20. From what I can tell, base beer plus one fruit = 20, and a Berliner with sour cherries won the category in 2008. It looks like it would be out of style in 23 because it "fits elsewhere" unless it had more than one fruit.
From 23:
"Beers with only one type of fruit, spice, herbs, vegetables, or smoke should be entered in Categories 20-22. Specialty meads or ciders should be entered in their respective categories"