Use quotes for cast

Author: rhshadrach

pandas/core/arrays/string_.py

@@ -23,7 +23,6 @@
 )
 from pandas._libs.arrays import NDArrayBacked
 from pandas._libs.lib import ensure_string_array
-from pandas._typing import npt
 from pandas.compat import (
     HAS_PYARROW,
     pa_version_under10p1,
@@ -84,6 +83,7 @@
         NumpyValueArrayLike,
         Scalar,
         Self,
+        npt,
         type_t,
     )
 
@@ -914,7 +914,7 @@ def _accumulate(self, name: str, *, skipna: bool = True, **kwargs) -> StringArra
         }[name]
 
         if self._hasna:
-            na_mask = cast(npt.NDArray[np.bool_], isna(ndarray))
+            na_mask = cast("npt.NDArray[np.bool_]", isna(ndarray))
             if np.all(na_mask):
                 return type(self)(ndarray)
             if skipna: