set type of Learner1D as annotated

Author: basnijholt

adaptive/learner/learner1D.py

@@ -303,7 +303,7 @@ def __init__(
         # The precision in 'x' below which we set losses to 0.
         self._dx_eps = 2 * max(np.abs(bounds)) * np.finfo(float).eps
 
-        self.bounds = list(bounds)
+        self.bounds = tuple(bounds)
         self.__missing_bounds = set(self.bounds)  # cache of missing bounds
 
         self._vdim: int | None = None