Force flux_unit to be unit instance

[pllim]

Force flux_unit to be unit instance instead of a str to be compatible with astropy v7.1

xref astropy/astropy#17586

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[mhvk]

A bit less obviously also an improvement in the code than for jdaviz - while you are at it, does it make sense to also re-assign in the one other case where self._validate_flux_unit is called? (I just did a code search, so am not sure whether it is in fact needed)

[pllim]

You mean here?

synphot_refactor/synphot/spectrum.py

Lines 1144 to 1146 in 63a63f2

	self._validate_flux_unit(pval.unit)
	outval = units.convert_flux(self._redshift_model(wave), pval,
	self._internal_flux_unit).value

In this case, pval is already a Quantity, so we do not have any problem with string.

[mhvk]

Yes, sorry I didn't look better before commenting!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.19%. Comparing base (262a309) to head (2466fe3).
Report is 6 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #403   +/-   ##
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  Coverage   97.19%   97.19%           
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  Files          17       17           
  Lines        2031     2031           
=======================================
  Hits         1974     1974           
  Misses         57       57           

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