conv_utils module has been moved again in TF 2.13, and can be imported as in
TF <= 2.5. The error raised is ImportError, which was added to the try/except
clause. ModuleNotFoundError is a subclass of ImportError; it is then removed.

… TF2.13

It seems that (de)serialization of h5 models in TF 2.13 has been changed:
custom objects, even with "register_keras_serializable", cannot be loaded.
Two solutions are possible:
- use "with_custom_object_scope()" to load a model with custom objects.
- save model in Keras format and not h5.

The second option was chosen because this format is now preferred for saving
models.

The power iteration test for Dense was sometimes failing due to a random
choice of kernel and initialization vector u. Even if np.random.seed(42)
was set at the beginning of the file.

To ensure a fully deterministic test (deterministic kernel and
initialization u), a random generator np.random.default_rng(42) was created
and used to create both kernel and u.
The results for Dense test are then deterministic, either for a single test
file or for the whole unittest. Note that this is the only test modified;
other tests of the file pass, they have not been changed with deterministic
initializations.