Remove allele_current_internal_id from training_data_for_ML_and_AI/alleles.tsv

[kimrutherford]

https://www.pombase.org/datasets/ai_and_ml_training_datasets

[kimrutherford]

I've removed the column from the file in the release, linked to from the AI/ML page.

I'll put a permanent fix in the code that generates the file before the next release.