Pyxirr

- Private Equity functions ([42](https://github.com/Anexen/pyxirr/issues/42))
- XNPV/NPV functions now accept rate as multidimensional array
- Explain Multiple IRR problem + provide utility functions for analysis
- XIRR improvements (prevent from values < -1, grid search + brentq as fallback)

- IRR improvements ([47](https://github.com/Anexen/pyxirr/pull/47))
- Python 3.12 support

- XNFV: suppress `InvalidPaymentsError` by passing `silent=True` flag ([40](https://github.com/Anexen/pyxirr/issues/40))

- CUMPRINC, CUMIPMT functions
- Upgrade maturin to v1

- Vectorized versions of numpy-financial functions
- Breaking change: fixed misspelling in keyword-only argument (pmt_at_beginning)

- Fix type annotations ([35](https://github.com/Anexen/pyxirr/issues/35))