Update cli.py with config file path operand error

[psgundla]

log_path issue for the storing of the config file while preprocessing.

~$ wsi_extraction --config configs/patch_extraction_tiles-l1-s256.yaml 
Traceback (most recent call last):
  File "/projects/envs/conda/psgudla/envs/cellvit_env/bin/wsi_extraction", line 8, in <module>
    sys.exit(main())
  File "/projects/envs/conda/psgudla/envs/cellvit_env/lib/python3.9/site-packages/pathopatch/wsi_extraction.py", line 31, in main
    configuration_parser.store_config()
  File "/projects/envs/conda/psgudla/envs/cellvit_env/lib/python3.9/site-packages/pathopatch/cli.py", line 686, in store_config
    with open(self.preprocessconfig.log_path / "config.yaml", "w") as yaml_file:
TypeError: unsupported operand type(s) for /: 'str' and 'str'