lifted suggested version

Did this, because with 3.0.1, the files
- catch_xmlwriter.cpp
- catch_string_manip.hpp
- catch_test_case_info.hpp

were missing

This led to some obvious and some obscure compile errors when compiling
with g++ 13.2.0 (std c++17 or c++20)
One of these errors being "Elaborated-type-specifier for a scoped enum
must not use the ‘class’ keyword"

Since this is a rather bad experience and debugging it is
time-consuming, I suggest to simply boost the recommended version in the
snippet which is likely copied by new Catch2 users

docs/cmake-integration.md

@@ -51,7 +51,7 @@ Include(FetchContent)
 FetchContent_Declare(
   Catch2
   GIT_REPOSITORY https://github.com/catchorg/Catch2.git
-  GIT_TAG        v3.0.1 # or a later release
+  GIT_TAG        v3.4.0 # or a later release
 )
 
 FetchContent_MakeAvailable(Catch2)