add datetime to maps

src/numpydantic/maps.py

@@ -64,5 +64,6 @@ python_to_nptyping = {
     int: dt.Int,
     bool: dt.Bool,
     complex: dt.Complex,
+    datetime: np.datetime64,
 }
 """Map from python types to nptyping types"""

src/numpydantic/ndarray.py

@@ -135,6 +135,15 @@ class NDArrayMeta(_NDArrayMeta, implementation="NDArray"):
             )
         return dtype
 
+    def _dtype_to_str(cls, dtype: Any) -> str:
+        if dtype is Any:
+            result = "Any"
+        elif issubclass(dtype, Structure):
+            result = str(dtype)
+        elif isinstance(dtype, tuple):
+            result = ", ".join([str(dt) for dt in dtype])
+        return result
+
 
 class NDArray(NPTypingType, metaclass=NDArrayMeta):
     """