Refactor: GPU: Texture: Replace eGPUTextureFormat by TextureFormat

This offers better semantic and safety of the API.

Part of #130632

Pull Request: https://projects.blender.org/blender/blender/pulls/142818

source/blender/python/gpu/gpu_py_framebuffer.cc

@@ -563,7 +563,8 @@ static PyObject *pygpu_framebuffer_read_color(BPyGPUFrameBuffer *self,
   PYGPU_FRAMEBUFFER_CHECK_OBJ(self);
   int x, y, w, h, channels;
   uint slot;
-  PyC_StringEnum pygpu_dataformat = {bpygpu_dataformat_items, GPU_RGBA8};
+  PyC_StringEnum pygpu_dataformat = {bpygpu_dataformat_items,
+                                     int(blender::gpu::TextureFormat::UNORM_8_8_8_8)};
   BPyGPUBuffer *py_buffer = nullptr;
 
   static const char *_keywords[] = {