Fix tests ORTModel

[fxmarty]

As per title.

[echarlaix]

thanks!

[echarlaix]

why this change ?

[fxmarty]

This was updated in a more recent commit. Basically self.use_past = len(self.key_value_input_names) > 0 +

optimum/optimum/onnxruntime/base.py

Lines 316 to 319 in 554e312

	if self.use_past is False or use_merged_no_cache:
	out_past_key_values = tuple(
	out_past_key_values[i : i + self.num_pkv] for i in range(0, len(out_past_key_values), self.num_pkv)
	)

does not really make sense and it results in failing tests.

We don't want an empty tuple as output for KV cache, but we want None.