[ENH] Optimize ROCKET GPU PPV calculation for 1.45× speedup

[Adityakushwaha2006]

Reference Issues/PRs

None

What does this implement/fix? Explain your changes.

This PR optimizes the _get_ppv() method in base.py for ROCKET GPU transformers by replacing integer operations with GPU optimised float32 operations

Performance Impact:

• PPV calculation: 1.45× faster (measured on GTX 1650 Ti)
  PPV calculation takes around 15-20% of the time in rocket aswell so extrapolating this speed up ,it should cause a ~5% speedup in the GPU variant. (both measures approximate)

Benchmark across dataset sizes:

Dataset	Size	Old (ms)	New (ms)	Speedup
Small	100×100	1.859	1.515	1.23×
Medium	1000×500	2.047	1.413	1.45×
Large	10000×100	2.133	1.285	1.66×

Verified Correctness:

• Mathematically equivalent to original
• All edge cases tested
• Zero breaking changes

Does your contribution introduce a new dependency? If yes, which one?

None

Any other comments?

GPUs handle floating point math much faster than integer counting, so switching to float operations gives a good speed boost.

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