Fix MPI not found for HDF5 built with CMake

[kwabenantim]

• Building HDF5 with autotools currently works okay. However, autotools support will be dropped in future versions of HDF5 in favour of CMake:

  • https://github.com/HDFGroup/hdf5/blob/README.md
  • Remove autotools files and docs HDFGroup/hdf5#5358.

• Building HDF5 with CMake also builds fine, but throws an error during Chaste config:

-- No HDF5 found in /home/runner/modules/opt/petsc/3.17.5/linux-gnu: looking for alternative HDF5 instead
CMake Error at /usr/share/cmake-3.22/Modules/FindPackageHandleStandardArgs.cmake:230 (message):
  Could NOT find MPI (missing: MPI_C_FOUND) (found version "3.1")
Call Stack (most recent call first):
  /usr/share/cmake-3.22/Modules/FindPackageHandleStandardArgs.cmake:594 (_FPHSA_FAILURE_MESSAGE)
  /usr/share/cmake-3.22/Modules/FindMPI.cmake:1830 (find_package_handle_standard_args)
  /home/runner/modules/opt/hdf5/1.14.1/cmake/hdf5-config.cmake:91 (find_package)
  /usr/share/cmake-3.22/Modules/FindHDF5.cmake:504 (find_package)
  CMakeLists.txt:507 (find_package)

[kwabenantim]

A possible fix might be explicitly enabling C in the Chaste CMakeLists.txt:

project (Chaste VERSION 2024.2 LANGUAGES C CXX)