BUG: Don’t test for truth but on None for kwargs

[bsipocz]

This is to fix the deprecation warnings coming from astropy, but I ended up adding this fix for more kwargs than just the Quantity ones, as it's better to be explicit.

    warnings.warn('The truth value of a Quantity is ambiguous. '
astropy.utils.exceptions.AstropyDeprecationWarning: The truth value of a Quantity is ambiguous. In the future this will raise a ValueError.

[codecov]

Codecov Report

Merging #360 (980e229) into main (249114f) will decrease coverage by 1.31%.
The diff coverage is 100.00%.

❗ Current head 980e229 differs from pull request most recent head bbde4d0. Consider uploading reports for the commit bbde4d0 to get more accurate results

@@            Coverage Diff             @@
##             main     #360      +/-   ##
==========================================
- Coverage   78.36%   77.05%   -1.32%     
==========================================
  Files          46       46              
  Lines        5506     5488      -18     
==========================================
- Hits         4315     4229      -86     
- Misses       1191     1259      +68     

Impacted Files	Coverage Δ
pyvo/dal/adhoc.py	67.22% <100.00%> (+0.63%)	⬆️
pyvo/dal/scs.py	54.01% <100.00%> (-14.56%)	⬇️
pyvo/dal/sia.py	53.52% <100.00%> (-11.93%)	⬇️
pyvo/dal/sla.py	53.21% <100.00%> (-11.34%)	⬇️
pyvo/dal/ssa.py	48.41% <100.00%> (-7.34%)	⬇️

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[andamian]

It works for me.