Importing lab fails with latest plum version v2.5.6

[davidwilby]

Importing lab results in an error raised in plum from version 2.5.6 (2.5.5) seems to be fine.

Error log from pytest collection:

    import lab as B
./python3.11/site-packages/lab/__init__.py:9: in <module>
    from .generic import *
./python3.11/site-packages/lab/generic.py:11: in <module>
    from .types import (
./python3.11/site-packages/lab/types.py:129: in <module>
    add_promotion_rule(NPNumeric, TFNumeric, TFNumeric)
./plum/plum/function.py:342: in _handle_not_found_lookup_error
    raise ex from None
./plum/plum/resolver.py:377: in resolve
    raise NotFoundLookupError(self.function_name, target, self.methods)
E   plum.resolver.NotFoundLookupError: `add_promotion_rule(<class 'numpy.ndarray'>, 
E   typing.Union[plum.type.ModuleType[tensorflow.Tensor], 
E   plum.type.ModuleType[tensorflow.Variable], 
E   plum.type.ModuleType[tensorflow.IndexedSlices], 
E   plum.type.ModuleType[keras.KerasTensor]], 
E   typing.Union[plum.type.ModuleType[tensorflow.Tensor], 
E   plum.type.ModuleType[tensorflow.Variable], 
E   plum.type.ModuleType[tensorflow.IndexedSlices], 
E   plum.type.ModuleType[keras.KerasTensor]])` could not be resolved.
E   
E   Closest candidates are the following:
E       add_promotion_rule(type1: object, type2: object, type_to: type) ->          
E       NoneType                                                                    
E           <function add_promotion_rule at 0x763607967380> @                       
E       ~/./plum/plum/promotion.py:137

[vabor112]

+1, same problem in https://github.com/geometric-kernels/GeometricKernels