update dtype check

Author: fbourgey

pandas/core/frame.py

@@ -11356,7 +11356,7 @@ def cov(
         """
         data = self._get_numeric_data() if numeric_only else self
         dtypes = [blk.dtype for blk in self._mgr.blocks]
-        if any(is_datetime64_any_dtype(d) or is_timedelta64_dtype(d) for d in dtypes):
+        if any(d.kind in "mM" for d in dtypes):
             msg = (
                 "DataFrame contains columns with dtype datetime64 "
                 "or timedelta64, which are not supported for cov."

pandas/core/internals/managers.py

@@ -1800,7 +1800,7 @@ def as_array(
                 arr = np.asarray(blk.values, dtype=dtype)
             else:
                 arr = np.array(blk.values, dtype=dtype, copy=copy)
-            if passed_nan and blk.dtype.kind in ["m", "M"]:
+            if passed_nan and blk.dtype.kind in "mM":
                 arr[isna(blk.values)] = na_value
 
             if not copy: