[gpu] Fix outdated os::Surface to show latest changes on the canvas

We have to mark the SkBitmap as modified (new generation ID) in
convert_image_to_surface() so we upload the bitmap changes as a new
texture in the GPU.

laf

@@ -1 +1 @@
-Subproject commit 968f0e4b935c77ec3701307ec963f5e058254424
+Subproject commit feba52e4ca7855219044e9fdf936ecb6b9b4d1ca

src/app/util/conversion_to_surface.cpp

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (c) 2020  Igara Studio S.A.
+// Copyright (c) 2020-2024  Igara Studio S.A.
 // Copyright (c) 2001-2018 David Capello
 //
 // This program is distributed under the terms of
@@ -20,6 +20,10 @@
 #include "os/surface.h"
 #include "os/surface_format.h"
 
+#if LAF_SKIA
+  #include "os/skia/skia_surface.h"
+#endif
+
 #include <algorithm>
 #include <stdexcept>
 
@@ -205,6 +209,12 @@ void convert_image_to_surface(
       ASSERT(false);
       throw std::runtime_error("conversion not supported");
   }
+
+#if LAF_SKIA
+  // Increment SkBitmap generation ID so it's re-uploaded to the GPU
+  // as a texture if it's needed.
+  static_cast<os::SkiaSurface*>(surface)->bitmap().notifyPixelsChanged();
+#endif
 }
 
 } // namespace app