updated TB-POC dataset and corresponding tests

src/ptbench/data/tbpoc/__init__.py

src/ptbench/data/tbpoc/datamodule.py

src/ptbench/data/tbpoc/fold_0.py

src/ptbench/data/tbpoc/fold_1.py

src/ptbench/data/tbpoc/fold_2.py

src/ptbench/data/tbpoc/fold_3.py

src/ptbench/data/tbpoc/fold_4.py

src/ptbench/data/tbpoc/fold_5.py

src/ptbench/data/tbpoc/fold_6.py

src/ptbench/data/tbpoc/fold_7.py

src/ptbench/data/tbpoc/fold_8.py

src/ptbench/data/tbpoc/fold_9.py

tests/test_tbpoc.py