CLN: Remove unused rewrite warning (#50403)

Author: rhshadrach

pandas/core/reshape/pivot.py

@@ -21,7 +21,6 @@
  Appender,
  Substitution,
 )
-from pandas.util._exceptions import rewrite_warning
 
 from pandas.core.dtypes.cast import maybe_downcast_to_dtype
 from pandas.core.dtypes.common import (
@@ -165,17 +164,7 @@ def __internal_pivot_table(
  values = list(values)
 
  grouped = data.groupby(keys, observed=observed, sort=sort)
- msg = (
- "pivot_table dropped a column because it failed to aggregate. This behavior "
- "is deprecated and will raise in a future version of pandas. Select only the "
- "columns that can be aggregated."
- )
- with rewrite_warning(
- target_message="The default value of numeric_only",
- target_category=FutureWarning,
- new_message=msg,
- ):
- agged = grouped.agg(aggfunc)
+ agged = grouped.agg(aggfunc)
 
  if dropna and isinstance(agged, ABCDataFrame) and len(agged.columns):
  agged = agged.dropna(how="all")