actually define max_wavelength (and min) while creating spectral_data object

[HaleySchuhl]

Describe your changes
actually define max_wavelength (and min) while creating spectral_data object within plantcv.geospatial.read_geotif. This attribute is checked while calculating indices, so add min & max to just find the min/max wavelength item available in the dictionary after it's been created.

Type of update
Is this a:

• feature enhancement

Associated issues
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[deepsource-io]

Here's the code health analysis summary for commits e82daa2..2c40a12. View details on DeepSource ↗.

Analysis Summary

Analyzer	Status	Summary	Link
Python	✅ Success		View Check ↗
Test coverage	✅ Success		View Check ↗

Code Coverage Report

Metric	Aggregate	Python
Branch Coverage	100%	100%
Composite Coverage	100%	100%
Line Coverage	100%	100%

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[k034b363]

Looks good to me!