Update catch2

Author: cschreib

tests/CMakeLists.txt

@@ -36,7 +36,7 @@ set(CMAKE_CXX_STANDARD 17) # enable C++17 in Catch2...
 
 FetchContent_Declare(catch2
                      GIT_REPOSITORY https://github.com/catchorg/Catch2.git
-                     GIT_TAG        v3.4.0)
+                     GIT_TAG        v3.9.1)
 FetchContent_MakeAvailable(catch2)
 
 set(RUNTIME_TEST_FILES