Don't glBindTexture() on viewports without effects

@reduz said there was another place that needed to be checked for a
similar issue but I have to admit I didn't understand.

This fixes #13337

drivers/gles3/rasterizer_canvas_gles3.cpp

@@ -1545,7 +1545,7 @@ void RasterizerCanvasGLES3::reset_canvas() {
 	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
 
 	//use for reading from screen
-	if (storage->frame.current_rt) {
+	if (storage->frame.current_rt && !storage->frame.current_rt->flags[RasterizerStorage::RENDER_TARGET_NO_SAMPLING]) {
 		glActiveTexture(GL_TEXTURE0 + storage->config.max_texture_image_units - 3);
 		glBindTexture(GL_TEXTURE_2D, storage->frame.current_rt->effects.mip_maps[0].color);
 	}