fix: use cwd in module path so imports in conf.py work

[NickLarsenNZ]

Fixes ModuleNotFoundError when trying to import other modules in conf.py:

import product1.versions as product1
import product2.versions as product2

products = [
    {
        "name": "product1",
        "versions": product1.versions,
    },
    {
        "name": "product2",
        "versions": product2.versions,
    },
]

The following error was being thrown:

Traceback (most recent call last):
  File "/home/runner/.local/bin/bake", line 8, in <module>
    sys.exit(main())
  File "/home/runner/.local/lib/python3.10/site-packages/image_tools/bake.py", line 173, in main
    conf = load_configuration(args.configuration)
  File "/home/runner/.local/lib/python3.10/site-packages/image_tools/args.py", line 195, in load_configuration
    spec.loader.exec_module(module)
  File "<frozen importlib._bootstrap_external>", line 883, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "/home/runner/work/dummy-docker-images/dummy-docker-images/./conf.py", line 7, in <module>
    import product1.versions as product1
ModuleNotFoundError: No module named 'product1'