Move variant usage to std

Since sdbusplus now uses std, it's cleaner just to
use the variant type directly not behind the namespace.

This was primarily done with sed commands

Tested-by: It builds

Change-Id: I87a90a2942cfc6da312cb0e045cce7cd40a644e5
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/include/VariantVisitors.hpp b/include/VariantVisitors.hpp
index 7a8677f..7b23977 100644
--- a/include/VariantVisitors.hpp
+++ b/include/VariantVisitors.hpp
@@ -17,6 +17,7 @@
 #pragma once
 #include <stdexcept>
 #include <string>
+#include <variant>
 
 struct VariantToFloatVisitor
 {