Fix/representation of model with DataFrame/Array parameters (unit8co#…

…1749)

* fix: added a test case when comparing the parameters for model string representation for pd.DataFrame and np.ndarray to avoid ambiguity when checking equality

* fix: using the proper operator to detect inequality

* fix: applying reviwer suggestion to simplify test

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Co-authored-by: Dennis Bader <dennis.bader@gmx.ch>

darts/models/forecasting/forecasting_model.py

@@ -1912,7 +1912,7 @@ def _get_model_description_string(self, include_default_params):
         changed_model_params = [
             (k, v)
             for k, v in self.model_params.items()
-            if include_default_params or v != default_model_params.get(k, None)
+            if include_default_params or np.any(v != default_model_params.get(k, None))
         ]
 
         model_name = self.__class__.__name__