List all GT4 Cup winners played on the Spa-Francorchamps Report.
CREATE TABLE "table1_30060356_3" (
  "event" real,
  "circuit" text,
  "gt3_pro_cup_winner" text,
  "gt3_pro_am_cup_winner" text,
  "gt3_citation_cup_winner" text,
  "gt4_cup_winner" text
);
SELECT "gt4_cup_winner" FROM "table1_30060356_3" WHERE "circuit"='Spa-Francorchamps Report';