Fixes shrimp cocktail recipe (#7047)

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## About The Pull Request

replaces the non-existent "pepper" reagent requirement with
"blackpepper"

## Why It's Good For The Game

Allows shrimp cocktails to be made

## Changelog

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🆑
fix: shrimp cocktail recipe
/🆑

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Co-authored-by: MarsMond <no@email>

code/modules/food/recipes_microwave.dm

@@ -1579,7 +1579,7 @@
 
 /datum/recipe/shrimpcocktail
 	fruit = list("tomato" = 2, "chili" = 2, "lemon" = 2)
-	reagents = list("water" = 5, "sodiumchloride" = 5, "pepper" = 5)
+	reagents = list("water" = 5, "sodiumchloride" = 5, "blackpepper" = 5)
 	items = list(
 		/obj/item/reagent_containers/food/snacks/shrimp,
 		/obj/item/reagent_containers/food/snacks/shrimp,