GPU: Slightly adjust PAL active range

Gets the PAR closer to the expected value of 59/94 with a divider of 4.

src/core/gpu.h

@@ -84,8 +84,8 @@ public:
     NTSC_HORIZONTAL_ACTIVE_END = 3288,
     NTSC_VERTICAL_ACTIVE_START = 16,
     NTSC_VERTICAL_ACTIVE_END = 256,
-    PAL_HORIZONTAL_ACTIVE_START = 487,
-    PAL_HORIZONTAL_ACTIVE_END = 3282,
+    PAL_HORIZONTAL_ACTIVE_START = 488,
+    PAL_HORIZONTAL_ACTIVE_END = 3300,
     PAL_VERTICAL_ACTIVE_START = 20,
     PAL_VERTICAL_ACTIVE_END = 308,
   };