ENG 9390: Files MIN_SAMPLES=1

[azahed98]

To support smaller validation datasets, the minimum dataset sample size is being reduced to 1 (we still need to make sure the dataset is nonempty). This is a single integer constant change.

$ cat ../test.jsonl 
{"text": "hi"}
$ together files check ../test.jsonl
{
    "is_check_passed": true,
    "message": "Checks passed",
    "found": true,
    "file_size": 15,
    "utf8": true,
    "line_type": true,
    "text_field": true,
    "key_value": true,
    "min_samples": true,
    "num_samples": 1,
    "load_json": true,
    "filetype": "jsonl"
}