src: add missing headers

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I6043ef792c2ce0a8e7584a73f83ca365ec61794d
diff --git a/src/PSUEvent.cpp b/src/PSUEvent.cpp
index d40dc54..f56b281 100644
--- a/src/PSUEvent.cpp
+++ b/src/PSUEvent.cpp
@@ -18,9 +18,16 @@
 
 #include <systemd/sd-journal.h>
 
+#include <boost/container/flat_map.hpp>
 #include <iostream>
+#include <memory>
 #include <sdbusplus/asio/connection.hpp>
 #include <sdbusplus/asio/object_server.hpp>
+#include <stdexcept>
+#include <string>
+#include <utility>
+#include <variant>
+#include <vector>
 
 PSUCombineEvent::PSUCombineEvent(
     sdbusplus::asio::object_server& objectServer, boost::asio::io_service& io,