Fixed Speculative Generator

[SinanAkkoyun]

Hey! Just wanted to test the speculative.py example and noticed that the speculative generator did not use the (I suppose new) sampler syntax, so this is the fix for that. ^^

# from
token, prob = ExLlamaV2Sampler.sample(logits, draft_settings, past, randoms[i])

# to:
token, prob, _ = ExLlamaV2Sampler.sample(logits, draft_settings, past, randoms[i], self.tokenizer)

# etc :)

[SinanAkkoyun]

Ah something went wrong bc I ran a test and commited the new cache, let me create a new PR with only one file changed...