Merge pull request #1526 from qiboteam/fix/global

Reset Transpiler When Setting Backends

src/qibo/backends/__init__.py

@@ -115,6 +115,7 @@ def _create_backend(cls):
     @classmethod
     def set_backend(cls, backend, **kwargs):
         cls._backend = construct_backend(backend, **kwargs)
+        cls._transpiler = None
         log.info(f"Using {cls._backend} backend on {cls._backend.device}")
 
     @classmethod