Fix memory leak

Author: Temmie3754

src_c/surface.c

@@ -1457,6 +1457,7 @@ surf_convert(pgSurfaceObject *self, PyObject *args)
             /* will be updated later, initialize to make static analyzer happy
              */
             int bpp = 0;
+            SDL_Palette *palette = SDL_AllocPalette(default_palette_size);
             SDL_PixelFormat format;
 
             memcpy(&format, surf->format, sizeof(format));
@@ -1566,15 +1567,14 @@ surf_convert(pgSurfaceObject *self, PyObject *args)
                     /* Give the surface something other than an all white
                      * palette.
                      */
-                    SDL_Palette *palette =
-                        SDL_AllocPalette(default_palette_size);
                     SDL_SetPaletteColors(palette, default_palette_colors, 0,
                                          default_palette_size);
                     format.palette = palette;
                 }
             }
             newsurf = SDL_ConvertSurface(surf, &format, 0);
             SDL_SetSurfaceBlendMode(newsurf, SDL_BLENDMODE_NONE);
+            SDL_FreePalette(palette);
         }
     }
     else {