feat: add set_device method to TN abstract backend

src/qibotn/backends/abstract.py

@@ -30,6 +30,9 @@ class QibotnBackend(NumpyBackend):
         if precision != self.precision:
             super().set_precision(precision)
 
+    def set_device(self, device):
+        self.device = device
+
     # @abstractmethod
     def configure_tn_simulation(self, **config):
         """Configure the TN simulation that will be performed."""