Add truthfulqa test data

tests/testdata/truthfulqa_gen-v0-greedy_until

+1a280973bbac2b7ac29dd64dddac474fb4749585f7de893483b4034814466c67
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tests/testdata/truthfulqa_gen-v0-res.json

+{"results": {"truthfulqa_gen": {"bleu acc": 0.0, "bleu acc_stderr": 0.0, "bleu diff": 0.0, "bleu diff_stderr": 0.0, "bleu max": 0.0, "bleu max_stderr": 0.0, "bleurt acc": 0.835985312117503, "bleurt acc_stderr": 0.012962704327492454, "bleurt diff": 0.14077322143090107, "bleurt diff_stderr": 0.005459888909582694, "bleurt max": -1.4399358725752065, "bleurt max_stderr": 0.0022126992369197133, "rouge1 acc": 0.0, "rouge1 acc_stderr": 0.0, "rouge1 diff": 0.0, "rouge1 diff_stderr": 0.0, "rouge1 max": 0.0, "rouge1 max_stderr": 0.0, "rouge2 acc": 0.0, "rouge2 acc_stderr": 0.0, "rouge2 diff": 0.0, "rouge2 diff_stderr": 0.0, "rouge2 max": 0.0, "rouge2 max_stderr": 0.0, "rougeL acc": 0.0, "rougeL acc_stderr": 0.0, "rougeL diff": 0.0, "rougeL diff_stderr": 0.0, "rougeL max": 0.0, "rougeL max_stderr": 0.0}}, "versions": {"truthfulqa_gen": 0}}
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tests/testdata/truthfulqa_mc-v0-loglikelihood

+1e07020e9cf41d46ed65312eb39d2b8e6599673d4f0d6b67c0d0eba0efb493bb
\ No newline at end of file

tests/testdata/truthfulqa_mc-v0-res.json

+{"results": {"truthfulqa_mc": {"mc1": 0.23255813953488372, "mc1_stderr": 0.01478915753108052, "mc2": 0.4462325560722362, "mc2_stderr": 0.004986523944692003}}, "versions": {"truthfulqa_mc": 0}}
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