Fix how node_label is passed by sncosmo models.

[jeremykubica]

Sncosmo models currently fail when node_label is given because it tries to parse it as one of the sncosmo parameters.

[github-actions[bot]]

Before [7121cf67]	After [5c617a3b]	Ratio	Benchmark (Parameter)
1.59±0.1ms	1.34±0.1ms	~0.84	benchmarks.TimeSuite.time_apply_passbands
4.24±0.06ms	4.40±1ms	1.04	benchmarks.TimeSuite.time_chained_evaluate
27.0±0.2μs	27.9±0.4μs	1.04	benchmarks.TimeSuite.time_make_new_salt3_model
15.6±0.2μs	16.2±0.09μs	1.04	benchmarks.TimeSuite.time_sample_x1_from_hostmass
1.34±0s	1.35±0.02s	1.01	benchmarks.TimeSuite.time_make_x1_from_hostmass
121±1μs	122±1μs	1.01	benchmarks.TimeSuite.time_sample_x0_from_distmod
1.95±0.2ms	1.94±2ms	1.00	benchmarks.TimeSuite.time_fnu_to_flam
8.98±0.05ms	9.02±0.08ms	1.00	benchmarks.TimeSuite.time_load_passbands
5.37±0.2ms	5.30±0.3ms	0.99	benchmarks.TimeSuite.time_evaluate_salt3_passbands
9.52±0.4ms	9.29±2ms	0.98	benchmarks.TimeSuite.time_evaluate_salt3_model

Click here to view all benchmarks.