standardize output format of xLSTMTime estimator for point predictions (#1978)

This PR standardizes the output format of the xLSTMTime estimator for
point predictions. This is in accordance with issue #1976

---------

Co-authored-by: Aryan Saini <starktony.2032@gmail.com>

Author: sanskarmodi8

pytorch_forecasting/models/xlstm/_xlstm.py

@@ -151,6 +151,7 @@ def forward(
         output = output.transpose(1, 2)
 
         output = output[0, ..., : self.hparams.output_size]
+        output = output.unsqueeze(-1)
         return self.to_network_output(prediction=output)
 
     @classmethod

pytorch_forecasting/models/xlstm/_xlstm_pkg.py

@@ -17,7 +17,6 @@ class xLSTMTime_pkg(_BasePtForecaster):
         "capability:pred_int": False,
         "capability:flexible_history_length": True,
         "capability:cold_start": False,
-        "tests:skip_by_name": "test_integration",
     }
 
     @classmethod