render/vulkan: Unref color transform on pass submit

We increment the ref counter of the color transform at the start of the
render pass. Decrement it at the end to not leak the color transform.

render/vulkan/pass.c

@@ -443,6 +443,7 @@ static bool render_pass_submit(struct wlr_render_pass *wlr_pass) {
 		wlr_log(WLR_ERROR, "Failed to sync render buffer");
 	}
 
+	wlr_color_transform_unref(pass->color_transform);
 	wlr_buffer_unlock(render_buffer->wlr_buffer);
 	rect_union_finish(&pass->updated_region);
 	free(pass);