use std::move_only_function

C++23 has a replacement for function2 in std::move_only_function.
Leverage that and remove the extra dependency.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I69fa59627b91fc1f640f7a688926bed7f138ca19
diff --git a/status.hpp b/status.hpp
index e3342d2..821d09c 100644
--- a/status.hpp
+++ b/status.hpp
@@ -1,8 +1,7 @@
 #pragma once
 
-#include <function2/function2.hpp>
-
 #include <cstdint>
+#include <functional>
 
 namespace ipmi_flash
 {
@@ -19,7 +18,7 @@
 class TriggerableActionInterface
 {
   public:
-    using Callback = fu2::unique_function<void(TriggerableActionInterface&)>;
+    using Callback = std::move_only_function<void(TriggerableActionInterface&)>;
 
     virtual ~TriggerableActionInterface() = default;