Do not garbage collect logp_dlogp function

Author: ricardoV94

pymc/step_methods/hmc/integration.py

@@ -42,6 +42,7 @@ def __init__(self, potential: QuadPotential, logp_dlogp_func):
         self._potential = potential
         # Sidestep logp_dlogp_function.__call__
         pytensor_function = logp_dlogp_func._pytensor_function
+        pytensor_function.vm.allow_gc = False
         # Create some wrappers for backwards compatibility during transition
         # When raveled_inputs=False is forbidden, func = pytensor_function
         if logp_dlogp_func._raveled_inputs: