stop installing manager header

Stop installing the manager header as it is no longer meant to be
exported, but rather used only internally within this repository.

Change-Id: I2ab21a31fd745e1b3e36fc39ffea5e26d373ff51
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/utils.hpp b/utils.hpp
index 50d320e..67380cd 100644
--- a/utils.hpp
+++ b/utils.hpp
@@ -1,8 +1,8 @@
 #pragma once
 
 #include "internal/sys.hpp"
+#include "manager.hpp"
 
-#include <blobs-ipmid/manager.hpp>
 #include <memory>
 #include <string>