Add tests for prediction code

tests/conftest.py

tests/data/evaluation/predict_training-test_0.txt

tests/data/evaluation/predict_training-train_0.txt

tests/data/evaluation/predict_training-val_0.txt

tests/data/prediction/charset.pkl

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...rediction/images/0dfe8bcd-ed0b-453e-bf19-cc697012296e.png

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...rediction/images/ffdec445-7f14-4f5f-be44-68d0844d0df1.png

tests/data/prediction/parameters.yml

tests/data/prediction/popp_line_model.pt

tests/data/training/models/best_0.pt

tests/data/training/models/last_3.pt

tests/data/training/training_dataset/charset.pkl

...g_dataset/images/0a34e13a-4ab0-4a91-8d7c-b1d8fee32628.png

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...g_dataset/images/0a70e14f-feda-4607-989c-36cf581ddff5.png

...g_dataset/images/0b2457c8-81f1-4600-84d9-f8bf2822a991.png

...g_dataset/images/fb3edb59-3678-49f8-8e16-8e32e3b0f051.png

...g_dataset/images/fe498de2-ece4-4fbe-8b53-edfce1b820f0.png