switch fmt::format to use std::format

fmt::format is supported in the c++ std. This will
help to remove fmt package dependency.

Change-Id: Ia3f5c607a348f062a0f112d5eae8b51ecc23fd37
Signed-off-by: Jayanth Othayoth <ojayanth@in.ibm.com>
diff --git a/extensions/phal/devtree_export.cpp b/extensions/phal/devtree_export.cpp
index ad21332..afa6e6a 100644
--- a/extensions/phal/devtree_export.cpp
+++ b/extensions/phal/devtree_export.cpp
@@ -1,10 +1,10 @@
 #include "fw_update_watch.hpp"
 
-#include <fmt/format.h>
-
 #include <phosphor-logging/elog-errors.hpp>
 #include <sdeventplus/event.hpp>
 
+#include <format>
+
 int main()
 {
     auto eventRet = 0;
@@ -27,7 +27,7 @@
     {
         using namespace phosphor::logging;
         log<level::ERR>(
-            fmt::format("Exception reported: [{}]", e.what()).c_str());
+            std::format("Exception reported: [{}]", e.what()).c_str());
     }
 
     return eventRet;