codecs.open() is deprecated. Use open() instead.

Testing with Python 3.14.2 shows this warning:
```
ddt.py:289: 8 warnings
test/test_functional.py: 2 warnings
  /data/builds/ul-mass-rebuild/components/python/ddt/build/amd64-3.14/ddt.py:289: DeprecationWarning: codecs.open() is deprecated. Use open() instead.
    with codecs.open(data_file_path, 'r', 'utf-8') as f:
```