[TEST] Update CG solver test to enable GPU backend

Switched the `use_gpu` configuration to `True` in the CG solver test, ensuring the test runs with GPU acceleration. Removed unused imports for cleanup.

test/test_modules/test_cg/test_cg_solver.py

@@ -1,11 +1,6 @@
 import gempy as gp
 from gempy.core.data.enumerators import ExampleModel
 from gempy.optional_dependencies import require_gempy_viewer
-from gempy_engine.core.data.interp_output import InterpOutput
-
-from test.verify_helper import gempy_verify_array
-import pytest
-from test.conftest import TEST_SPEED, TestSpeed
 
 PLOT = True
 
@@ -18,7 +13,7 @@ def test_generate_greenstone_model():
         gempy_model=model,
         engine_config=gp.data.GemPyEngineConfig(
             backend=gp.data.AvailableBackends.PYTORCH,
-            use_gpu=False,
+            use_gpu=True,
             dtype='float32'
         )
     )