fixed nan edge-case in report api

Author: rabah-khalek

giskard_vision/landmark_detection/tests/report.py

@@ -69,6 +69,7 @@ def to_dataframe(self, summary: Optional[bool] = False):
             raise GiskardImportError(["pandas"]) from e
 
         df = pd.DataFrame(self.results)
+        df.dropna(inplace=True)  # in case the model failed to predict for instance
 
         for col in ["metric_value", "prediction_time", "prediction_fail_rate"]:
             col_name = f"Best({col})"