clang-format: update to latest from docs repo

The openbmc/docs/style/cpp/.clang-format has been updated to support
clang-format10, take this opportunity to update it in this repo.

Change-Id: I9e6b9853bf4cd7399b1ae504ea3be5093d763fee
Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
diff --git a/download_manager.hpp b/download_manager.hpp
index b53fc2b..9f7d1cf 100644
--- a/download_manager.hpp
+++ b/download_manager.hpp
@@ -3,6 +3,7 @@
 #include "xyz/openbmc_project/Common/TFTP/server.hpp"
 
 #include <sdbusplus/bus.hpp>
+
 #include <string>
 
 namespace phosphor