[flatbush] add release v1.4.0

[chusitoo]

Motivation

Performance improvements and better test coverage

Details

Introduce SIMD in certain hot paths.
Reduced branching by moving parts of the logic to compile time
Use different strategies for small and large inputs

• Changes comply with the maintainer guide.
• SHA512s are updated for each updated download.
• The "supports" clause reflects platforms that may be fixed by this new version.
• Any fixed CI baseline entries are removed from that file.
• Any patches that are no longer applied are deleted from the port's directory.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Only one version is added to each modified port's versions file.