v0.4.0-rc4

Pre-release to generate release wheels

What's Changed

• Fix: Incorrect constructor reference for NeptuneGraph by @andy-k-improving in #17
• FIX: Pin core dependencies versions by @andy-k-improving in #18
• Update environment variables to use NETWORKX_ prefix by @acarbonetto in #19
• Public package to PyPi by @acarbonetto in #20
• CI: Publish .whl to Pypi via openID by @andy-k-improving in #8

Full Changelog: v0.4.0-rc3...v0.4.0-rc4