What is the build date of the model with a PRR Class of brs24?
CREATE TABLE "baldwin_locomotive_works" (
  "prr_class" text,
  "builder_s_model" text,
  "build_date" text,
  "total_produced" real,
  "wheel_arrangement" text,
  "service" text,
  "power_output" text
);
SELECT "build_date" FROM "baldwin_locomotive_works" WHERE "prr_class"='brs24';