Pyco2sys

* Removed self-dependency in pyproject.toml.

* Numpy version restriction to <2 removed, as Autograd incompatibility has been resolved.

* Numpy version restricted to <2 to work around Autograd incompatibility (removal of msort function).

***New features***

* Added `"dlnfCO2_dT"` and `"dlnpCO2_dT"` results, the theoretical effect of temperature on the natural log of <i>ƒ</i>CO₂ and <i>p</i>CO₂.
* Added the [PLR18](../refs/p) parameterisation of the carbonic acid constants for sea-ice brines.

***Default options***

* Reverted default `opt_k_carbonic` to `10` (i.e., [LDK00](../refs/l)) for consistency with the best practice guide.

***Bug fixes***

* Updated `pyco2.equilibria.p1atm.kH2CO3_NBS_MCHP73` (used for `opt_k_carbonic` options `6` and `7`) to update any salinity values less than 10^–16 to be 10^–16, because zero salinities give a NaN for <i>K</i>₂, which causes problems for Autograd. This should not make any practical difference, because the parameterisation is only valid for salinities above 19.
* Added `opt_pressured_kCO2` to results dict and incorporated it correctly into the uncertainty propagation functions.

***Technical***

* Updated from building with setup.py to pyproject.toml.

***New features***

* Added `opt_pressured_kCO2` to enable pressure corrections for the fugacity factor and CO₂ solubility constant following [W74](https://PyCO2SYS.readthedocs.io/en/latest/refs/#w). These have been added to CO2SYS-MATLAB by Jon Sharp at the same time with consistent results (differences less than 10⁻⁴ %). These pressure corrections are not enabled by default, for consistency with previous versions.

***Bug fixes***

* Fixed logicals in `solve.core()` that had meant no results were returned for parameter type combinations `7, 10`, `7, 11`, `8, 10` and `8, 11`.
* Updated Autograd version for compatibility with Python 3.11.

*Changes in v1.8.1*

***Breaking changes***

* For consistency with other settings, `buffers_mode` kwarg key changed to `opt_buffers_mode` and its values are now integers rather than strings.

***New features***

* Adds new `par1_type` / `par2_type` options `10` and `11` for saturation states with respect to calcite and aragonite.
* Adds [KSK18](../refs/k) parameterisation for estimating total borate from salinity.

***Dependencies***

* Switched to Autograd v1.4.