[BUG] Move backend setting to forward function for consistency

Relocated `change_backend_gempy` call to `run_gempy_forward` to ensure proper backend configuration during execution. Removed redundant imports to clean up the module.

Author: Leguark

gempy_probability/modules/forwards/_gempy_fw.py

@@ -1,14 +1,11 @@
-import torch
-from pyro.distributions import Distribution
-
-import gempy_engine
-from gempy.modules.data_manipulation import interpolation_input_from_structural_frame
 import gempy as gp
+import gempy_engine
+from gempy_engine.core.backend_tensor import BackendTensor
 from gempy_engine.core.data.interpolation_input import InterpolationInput
 
 
 def run_gempy_forward(interp_input: InterpolationInput, geo_model: gp.data.GeoModel) -> gp.data.Solutions:
-
+    BackendTensor.change_backend_gempy(engine_backend=gp.data.AvailableBackends.PYTORCH)
     # compute model
     sol = gempy_engine.compute_model(
         interpolation_input=interp_input,

tests/test_prob_model/test_prob_factory.py

@@ -50,7 +50,6 @@ def test_prob_model_factory() -> None:
         gempy_model=geo_model,
         validate_serialization=False
     )
-    BackendTensor.change_backend_gempy(engine_backend=gp.data.AvailableBackends.PYTORCH)
 
     # 1) Define your priors
     model_priors = {