Cavitometer-deconvolve

Minor GUI improvements.

- Support Excel files for data input and probe sensitivities.
- Removed setuptools config files.
- Basic GUI.

- [numpy.fft.rfft](https://numpy.org/doc/stable/reference/generated/numpy.fft.rfft.html) and removed one-sided <-> two-sided transformations.
- [pandas.read_csv](https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.read_csv.html) for reading data.
- Including pyproject.toml file.
- Switched to [pytest](https://docs.pytest.org) for unit testing.