Fix enum/int mismatch

src/ppu.c

@@ -220,7 +220,7 @@ int nes_ppu_init(nes_ppu* ppu, const nes_cart* cart) {
     return 0;
 }
 
-int nes_ppu_run(nes_ppu* ppu, int cycles) {
+nes_ppu_Result nes_ppu_run(nes_ppu* ppu, int cycles) {
     nes_ppu_Result result = ppu_Result_Running;
 
     int next_cycle = ppu->cycle + cycles;