remove fixed spectral_order from GNIRSXD determineDistortion() test

Author: chris-simpson

geminidr/gnirs/tests/crossdispersed/test_determine_distortion.py

@@ -25,7 +25,6 @@
     "min_snr": 10.,
     "nsum": 10,
     "min_line_length": 0.6,
-    "spectral_order": 2,
     "debug_reject_bad": True
 }