Use pint to keep track of different units

[charlesbmi]

Describe the new feature or enhancement

It would be helpful (especially for new contributers) to know exactly what units different variables use, and how to convert between the units. For example people seem to cite absorption in dB/cm or with MHz, etc.

Describe your proposed implementation

Use https://github.com/hgrecco/pint to annotate units. This would, e.g., replace utility functions like

neurotechdevkit/src/neurotechdevkit/results/_metrics.py

Lines 292 to 329 in 6e53d78

	class Conversions:
	"""A set of unit-of-measurement conversion tools."""
	@staticmethod
	def convert(from_uom, to_uom, value):
	"""Convert a value from one unit-of-measurement to another.
	Conversions are requested using specific strings for the starting and desired
	unit-of-measurement. The reason for this is that attempts to specify function
	names that indicate a single conversion have resulted in overly verbose or
	difficult names. Units-of-measurement can be written much more succinctly in a
	string than in a function name, which results in much more readable function
	usage with strings.
	Currently supported conversions:
	* W/m² to mW/cm²
	* W/m² to W/cm²
	If an unsupported conversion is requested, an exception will be raised.
	Args:
	from_uom: A string containing unit-of-measurement from which to convert.
	to_uom: A string containing unit-of-measurement to which to convert.
	value: the value to be converted.
	Raises:
	ValueError: If an unsupported conversion is requested.
	Returns:
	The converted value.
	"""
	if from_uom == "W/m²" and to_uom == "mW/cm²":
	return value * 0.1
	if from_uom == "W/m²" and to_uom == "W/cm²":
	return value * 1e-4
	raise ValueError(f"Unsupported conversion: from '{from_uom}' to '{to_uom}'")

and

neurotechdevkit/src/neurotechdevkit/materials.py

Lines 65 to 76 in 6e53d78

	We convert the absorption coefficient from Np/m/Hz to dB/m/Hz
	multiplying it by 8.6860000037.
	Args:
	frequency (float): in Hz
	Returns:
	float: attenuation in dB/cm/MHz
	"""
	attenuation = self.a0 * (frequency / 1e6) ** self.b # Np/m
	db_attenuation = attenuation * NEPER_TO_DECIBEL # dB/m
	return db_attenuation / 100 # convert from dB/m to dB/cm

Describe possible alternatives

https://github.com/python-quantities/python-quantities also looks like a suitable alternative. Seems slightly less active, with less frequent releases and fewer stars.