Expose NegativeBinomial from top-level distributions module (#2196)

Author: dylanhmorris

numpyro/distributions/__init__.py

@@ -11,6 +11,7 @@
     BetaNegativeBinomial,
     DirichletMultinomial,
     GammaPoisson,
+    NegativeBinomial,
     NegativeBinomial2,
     NegativeBinomialLogits,
     NegativeBinomialProbs,
@@ -194,6 +195,7 @@
     "MultinomialProbs",
     "MultivariateNormal",
     "MultivariateStudentT",
+    "NegativeBinomial",
     "NegativeBinomial2",
     "NegativeBinomialLogits",
     "NegativeBinomialProbs",