Fix compilation with fmtlib 10

Det/VPDet/src/component/legacy/VeloMotionSystemFromYaml.cpp

 /*****************************************************************************\
-* (c) Copyright 2022 CERN for the benefit of the LHCb Collaboration           *
+* (c) Copyright 2022-2023 CERN for the benefit of the LHCb Collaboration      *
 *                                                                             *
 * This software is distributed under the terms of the GNU General Public      *
 * Licence version 3 (GPL Version 3), copied verbatim in the file "COPYING".   *
@@ -20,11 +20,15 @@
 #include <XmlTools/IXmlSvc.h>
 #include <atomic>
 #include <fmt/format.h>
+#include <fmt/ostream.h>
 #include <mutex>
 #include <string>
 #include <tuple>
 #include <yaml-cpp/yaml.h>
 
+// Allow formatting of YAML::Node through `operator<<` (https://fmt.dev/latest/api.html#std-ostream-support)
+template <> struct fmt::formatter<YAML::Node> : ostream_formatter {};
+
 namespace LHCb {
   namespace DetDesc {
     /// Algorithm to extract the Velo Motion System data from YAML conditions and