PF unit-tests do NOT build with pio2_6_9 or later

This is in the context of ctsm5.4.044 which uses cime6_2_2. If I update pio beyond pio2_6_8 the PF unit tests from cime fail as follows:

```
CMake Warning (dev) at /glade/u/apps/derecho/25.10/spack/opt/spack/cmake/3.31.8/gcc/12.5.0/jijp/share/cmake-3.31/Modules/CMakeFindDependencyMacro.cmake:76 (find_package):
Policy CMP0074 is not set: find_package uses _ROOT variables.
Run "cmake --help-policy CMP0074" for policy details. Use the cmake_policy
command to set the policy and suppress this warning.

CMake variable FARGPARSE_ROOT is set to:

/glade/campaign/cesm/cesmdata/tools/pFUnit/pFUnit4.8.0_derecho_Intel2023.2.1_noMPI_noOpenMP/FARGPARSE-1.6

For compatibility, CMake is ignoring the variable.
Call Stack (most recent call first):
/glade/campaign/cesm/cesmdata/tools/pFUnit/pFUnit4.8.0_derecho_Intel2023.2.1_noMPI_noOpenMP/PFUNIT-4.8/cmake/PFUNITConfig.cmake:78 (find_dependency)
/glade/work/erik/ctsm_worktrees/b4b-dev/cime/CIME/non_py/src/CMake/CIME_utils.cmake:88 (find_package)
CMakeLists.txt:14 (include)
This warning is for project developers. Use -Wno-dev to suppress it.

CMake Error at CMakeLists.txt:18 (find_package):
By not providing "FindNetCDF.cmake" in CMAKE_MODULE_PATH this project has
asked CMake to find a package configuration file provided by "NetCDF", but
CMake did not find one.

Could not find a package configuration file provided by "NetCDF" (requested
version 4.7.4) with any of the following names:

NetCDFConfig.cmake
netcdf-config.cmake

Add the installation prefix of "NetCDF" to CMAKE_PREFIX_PATH or set
"NetCDF_DIR" to a directory containing one of the above files. If "NetCDF"
provides a separate development package or SDK, be sure it has been
installed.

-- Configuring incomplete, errors occurred!
make: *** [Makefile:6679: cmake_check_build_system] Error 1' from dir '/glade/work/erik/ctsm_worktrees/b4b-dev/src/unit_tests.temp/__command_line_test__/__command_line_test__'
```