CMake: Skip expensive boost test

This has been finally fixed upstream sometime in late 2018 [1], and this
runtime check is very expensive. Let us skip it for a safe, good
version. I have chosen 1.74 semi randomly because it has been released
in 2020 and is the boost version found in Debian 11.

[1] boostorg/serialization#79 (comment)

cmake/configure/configure_2_boost.cmake

@@ -194,7 +194,7 @@ MACRO(FEATURE_BOOST_FIND_EXTERNAL var)
       RESET_CMAKE_REQUIRED()
     ENDIF() # DEAL_II_WITH_ZLIB
 
-    IF(DEAL_II_ALLOW_PLATFORM_INTROSPECTION)
+    IF(${BOOST_VERSION} VERSION_LESS 1.74.0 AND DEAL_II_ALLOW_PLATFORM_INTROSPECTION)
       #
       # Test that Boost.Serialization is usable.
       #