Implement PyStubType for PyArrayDescr (#183)

Closes: #182

---------

Co-authored-by: Toshiki Teramura <toshiki.teramura@gmail.com>

Author: terraputix

pyo3-stub-gen/src/stub_type/numpy.rs

@@ -1,7 +1,8 @@
 use super::{PyStubType, TypeInfo};
 use maplit::hashset;
 use numpy::{
-    ndarray::Dimension, Element, PyArray, PyReadonlyArray, PyReadwriteArray, PyUntypedArray,
+    ndarray::Dimension, Element, PyArray, PyArrayDescr, PyReadonlyArray, PyReadwriteArray,
+    PyUntypedArray,
 };
 
 trait NumPyScalar {
@@ -73,3 +74,12 @@ where
         PyArray::<T, D>::type_output()
     }
 }
+
+impl PyStubType for PyArrayDescr {
+    fn type_output() -> TypeInfo {
+        TypeInfo {
+            name: "numpy.dtype".into(),
+            import: hashset!["numpy".into()],
+        }
+    }
+}