Replace interface{} with any (#25686) (#25687)

Same perl replacement as https://github.com/go-gitea/gitea/pull/25686
but for 1.20 to ease future backporting.

routers/web/repo/milestone.go

@@ -256,7 +256,7 @@ func DeleteMilestone(ctx *context.Context) {
 		ctx.Flash.Success(ctx.Tr("repo.milestones.deletion_success"))
 	}
 
-	ctx.JSON(http.StatusOK, map[string]interface{}{
+	ctx.JSON(http.StatusOK, map[string]any{
 		"redirect": ctx.Repo.RepoLink + "/milestones",
 	})
 }