BUG: add warning when creating Series from Series with dtype keyword

When creating Series from another Series `dtype` keyword is not not used
Make warning for users who expect it to have effect. See GH #59060.

Author: taranarmo

pandas/core/series.py

@@ -451,6 +451,12 @@ def __init__(
                 data = data.reindex(index)
                 copy = False
                 data = data._mgr
+            if dtype is not None:
+                warnings.warn(
+                    "dtype keyword is not used for Series created from Series",
+                    RuntimeWarning,
+                    stacklevel=2,
+                )
         elif isinstance(data, Mapping):
             data, index = self._init_dict(data, index, dtype)
             dtype = None