[data.indian] Use type-friendly name

src/ptbench/data/indian/fold-0.json

src/ptbench/data/indian/fold-1.json

src/ptbench/data/indian/fold-2.json

src/ptbench/data/indian/fold-3.json

src/ptbench/data/indian/fold-4.json

src/ptbench/data/indian/fold-5.json

src/ptbench/data/indian/fold-6.json

src/ptbench/data/indian/fold-7.json

src/ptbench/data/indian/fold-8.json

src/ptbench/data/indian/fold-9.json

src/ptbench/data/indian/fold_0.py

src/ptbench/data/indian/fold_1.py

src/ptbench/data/indian/fold_2.py

src/ptbench/data/indian/fold_3.py

src/ptbench/data/indian/fold_4.py

src/ptbench/data/indian/fold_5.py

src/ptbench/data/indian/fold_6.py

src/ptbench/data/indian/fold_7.py

src/ptbench/data/indian/fold_8.py

src/ptbench/data/indian/fold_9.py