Update dependencies, remove Python 3.9 support, and update version to 0.9.4.
Python Support:
* Removed support for Python 3.9 in pyproject.toml.
Version Update:
*Updated HSDS_VERSION to 0.9.4 in hsds/basenode.py.
*Updated project version to 0.9.4 in pyproject.toml.
Dependencies:
* Updated numpy to >=2.0.0 in pyproject.toml.
* Replaced requests-unixsocket2 with requests-unixsocket in pyproject.toml.
* Updated requirements.txt with specific versions for all dependencies.