Improve C++ test

What is the bug

The C++ test code for `mo_util_stride. uses the experimental standard library.
The filesystem standard library is automatically linked in C++17.

How do you fix it

Replace with standard library.

How urgent is the bugfix

• I need it as soon as possible
• I can wait for a couple of days
• None of my current codes is directly affected

Mandatory steps before review

• Gitlab CI passes (Hint: use make format for linting)
• Bugfix is covered by additional unit tests
• Mark the merge request as ready by removing Draft:

Mandatory steps before merge

• Test coverage does not decrease
• Reviewed by a maintainer
• Incorporate review suggestions
• Prior to merging, please remove any boilerplate from the MR description, retaining only the What is the bug and How do you fix it section to maintain
• Remember to edit the commit message and select the proper changelog category (feature/bugfix/other)

You are not supposed to merge this request by yourself, the maintainers of fortan-support take care of this action!

cmake/gtest_helper.cmake

@@ -31,7 +31,7 @@ function(fs_add_c_test test_name)
   add_executable("CTest_${test_name}" ${ARG_SOURCES})
   target_link_libraries(
     "CTest_${test_name}" PRIVATE fortran-support::fortran-support
-                                 GTest::gtest_main stdc++fs)
+                                 GTest::gtest_main)
   add_test(NAME "CTest_${test_name}" COMMAND "CTest_${test_name}" ${ARG_ARGS})
   set_property(TEST "CTest_${test_name}" PROPERTY LABELS C)
   set_target_properties("CTest_${test_name}"