[FIX] missing f-string in dataset features error message (#294)

# Description
The error message in `get_dataset_features` was missing an f prefix on
the string containing {`dataset_id}`. This caused users to see the
literal text {dataset_id} instead of the actual dataset ID when a
dataset had no features. Added the f prefix to correctly interpolate the
variable.

Co-authored-by: igennova <luckynegi025@gmail.com>

Author: igennova

src/routers/openml/datasets.py

@@ -326,7 +326,7 @@ async def get_dataset_features(
             raise DatasetProcessingError(msg)
         msg = (
             "No features found. "
-            "Dataset {dataset_id} did not contain any features, or we could not extract them."
+            f"Dataset {dataset_id} did not contain any features, or we could not extract them."
         )
         raise DatasetNoFeaturesError(msg)
     return features