Fix for a rel csv file given in relative path

[sungeunbae]

When you run realisation_to_srf.py from the path where the rel csv file is located and give a relative path (ie. just the file name), it will get confused when it sees mkdir because os.path.dirname(rel_csv) is an empty string.

Traceback (most recent call last):
...
  File "/home/seb56/Pre-processing/srf_generation/input_file_generation/realisation_to_srf.py", line 88, in create_stoch
    os.makedirs(out_dir, exist_ok=True)
  File "/home/seb56/miniforge3/envs/mamba310/lib/python3.10/os.py", line 225, in makedirs
    mkdir(name, mode)
FileNotFoundError: [Errno 2] No such file or directory: ''

or

Traceback (most recent call last):
...
File "/home/seb56/Pre-processing/srf_generation/input_file_generation/realisation_to_srf.py", line 1016, in generate_sim_params_yaml
os.makedirs(os.path.dirname(sim_params_file), exist_ok=True)
File "/home/seb56/miniforge3/envs/mamba310/lib/python3.10/os.py", line 225, in makedirs
mkdir(name, mode)
FileNotFoundError: [Errno 2] No such file or directory: ''

[sungeunbae]

This also include a fix for Jenkins caused by the change to qcore data download