Migrate to boost 1.73

- Poky already had moved to 1.73, and bmcweb is lagging behind.
- There are lot of improvements in 1.73(especially better support
  for c++20 standard) that can be leveraged by developer community,
  so migrating the dependency boost library to 1.73

Tested By:
- Compiled in all sdks, and unit tests passed.

Signed-off-by: Manojkiran Eda <manojkiran.eda@gmail.com>
Change-Id: Ia1c53bb3c96151d41c18b67a6d0c82edb756e7fd
diff --git a/CMakeLists.txt b/CMakeLists.txt
index ba52fad..6e628d4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -265,7 +265,8 @@
     set (CMAKE_PREFIX_PATH ${CMAKE_BINARY_DIR}/prefix ${CMAKE_PREFIX_PATH})
 endif ()
 
-find_package (Boost 1.71 REQUIRED)
+find_package (Boost 1.73 REQUIRED)
+message (BOOST_VERSION = ${Boost_VERSION})
 include_directories (SYSTEM ${BOOST_SRC_DIR})
 
 # add_definitions(-DBOOST_ASIO_ENABLE_HANDLER_TRACKING)
@@ -273,10 +274,7 @@
 add_definitions (-DBOOST_BEAST_USE_STD_STRING_VIEW)
 add_definitions (-DBOOST_ERROR_CODE_HEADER_ONLY)
 add_definitions (-DBOOST_SYSTEM_NO_DEPRECATED)
-message (BOOST_VERSION = ${Boost_VERSION})
-if ("${Boost_VERSION}" STREQUAL "107100")
-    add_definitions (-DBOOST_ASIO_NO_DEPRECATED)
-endif ()
+add_definitions (-DBOOST_ASIO_NO_DEPRECATED)
 add_definitions (-DBOOST_ALL_NO_LIB)
 add_definitions (-DBOOST_NO_RTTI)
 add_definitions (-DBOOST_NO_TYPEID)