Updated data type check in base ETL transformer

Author: Ken Lippold

src/hydroserverpy/etl/transformers/base.py

@@ -156,7 +156,7 @@ def apply_data_transformations(
 
         transformed_series = series
 
-        if series.dtype == "object":
+        if pd.api.types.is_string_dtype(series):
             transformed_series = pd.to_numeric(transformed_series, errors="coerce")
 
         for transformation in path.data_operations: