Append v0.3.0 release with #344

Update version to v0.4.0 (#319)

## Summary
- Version bump from v0.3.0 to v0.4.0 across all version files
- Updated NEWS.md with v0.4.0 release notes, moved v0.3.0 notes to
HISTORY.md
- Updated runtime API version (MINOR 2 -> 4) in version.h to align with
project version

## Release Notes
* Native serialization support for Indexes (#300)
* Clang-21 compiler support with gcc-11 headers for shared library
builds
* Amazonlinux2 support for shared/static library dropped
* Consolidated to publish only minimal necessary shared library (14 ->
6) and runtime bindings (2 -> 1) release artifacts

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Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

v0.3.0 update (#295)

v0.2.0 update (#270)

Pending merge of #269 , #251 , and maybe #267

Enable IVF index Save/Load functionality with dense clusters (#260)

This PR implements save and load functionality for IVF indices using
dense cluster storage, enabling serialization and restoration of both
static and dynamic IVF indices without requiring the original dataset.

Changes:

Added save/load support for DenseClusteredDataset, IVFIndex, and
DynamicIVFIndex
Implemented directory-based and stream-based serialization formats
Added comprehensive test coverage across C++ unit tests, integration
tests, and Python bindings

v0.1.0 update (#250)

Update to v0.0.11 (#230)

Add functions to check NaN values in data span (#178)

Fix omp threading size (#172)

This PR fixes OMPThreadPool size bug, which previously calls
`omp_get_num_threads` and always returned a value of one.

change to v0.0.9 (#169)

Bump versions in files to 0.0.9