Bump version to 4.3.0 (MIT-LCP#535)

This change updates the version and changelog for the v4.3.0 release.

Adds changelog for v4.2.0. (MIT-LCP#529)

This pull request adds a changelog for `v4.2.0`. The changelog is based
on the following auto-generated summary of merge commits generated by
GitHub:

```
## What's Changed

* bug-fix: Numpy ValueError when cheking empty list equality by @ajadczaksunriselabs in MIT-LCP#459
* bug-fix: Pandas set indexing error by @ajadczaksunriselabs in MIT-LCP#460
* fix for MIT-LCP/issues/452 by @tecamenz in MIT-LCP#465
* Use numpydoc to render documentation by @SnoopJ in MIT-LCP#472
* build(deps): bump readthedocs-sphinx-search from 0.1.1 to 0.3.2 in /docs by @dependabot in MIT-LCP#477
* Update style by @bemoody in MIT-LCP#482
* Fix NaN handling in Record.adc, and other fixes by @bemoody in MIT-LCP#481
* Set upper bound on Numpy version (numpy = ">=1.10.1,<2.0.0"). Ref MIT-LCP#493. by @tompollard in MIT-LCP#494
* Update actions to use actions/checkout@v3 and actions/setup-python@v4. by @tompollard in MIT-LCP#495
* Fix: Indent code to ensure 'j' is within for-loop in GQRS algorithm by @tompollard in MIT-LCP#499
* Add write_dir argument to csv_to_wfdb. Fixes MIT-LCP#67. by @tompollard in MIT-LCP#492
* Fix warnings by @cbrnr in MIT-LCP#502
* README improvements by @bemoody in MIT-LCP#503
* Change in type promotion. Fixes to annotation.py by @tompollard in MIT-LCP#506
* Use uv by @cbrnr in MIT-LCP#504
* Change in type promotion. Fixes to _signal.py by @tompollard in MIT-LCP#507
* Test round-trip write/read of supported binary formats by @bemoody in MIT-LCP#509
* Corrected typo and extended allowed types for MultiSegmentRecord by @agent3gatech in MIT-LCP#514
* Allow expanded physical signal in `calc_adc_params` by @briangow in MIT-LCP#512
* Add capability to write signal with unique `samps_per_frame` to `wfdb.io.wrsamp` by @briangow in MIT-LCP#510
* Fix selection of channels when converting to EDF by @SamJelfs in MIT-LCP#519
* Change in type promotion introduced in Numpy 2.0. Fixes to edf.py. by @tompollard in MIT-LCP#527
* Bump dependencies for NumPy 2 compatibility by @cbrnr in MIT-LCP#511
* Bump version to v4.2.0 and update notes on creating new releases by @tompollard in MIT-LCP#497

## New Contributors

* @ajadczaksunriselabs made their first contribution in MIT-LCP#459
* @tecamenz made their first contribution in MIT-LCP#465
* @SnoopJ made their first contribution in MIT-LCP#472
* @dependabot made their first contribution in MIT-LCP#477
* @agent3gatech made their first contribution in MIT-LCP#514
* @SamJelfs made their first contribution in MIT-LCP#519

**Full Changelog**: MIT-LCP/wfdb-python@v4.1.2...v4.2.0
```

Merge pull request MIT-LCP#457 from MIT-LCP/tp/bump_to_4_1_2

Bump version to 4.1.2. Add release notes to docs.

Merge pull request MIT-LCP#448 from cbrnr/remove-version-caps

Remove version caps

Version 4.1.0

Update version to 4.0.0 (MIT-LCP#398)

* Add more metadata fields to project metadata

* Add upload instructions to README

Merge pull request MIT-LCP#321 from hofaflo/no-sklearn

Remove dependency on scikit-learn

Update version to 3.4.0

Updates version

Bumps version for new release