Release v0.9.1

What's Changed

• Setup: add requirements-dev with pre-commit by @Giuseppe5 in #581
• CI update by @Giuseppe5 in #570
• Fix (brevitas_examples/bnn_pynq): missing 4b resnet18 link and hash fn by @volcacius in #583
• Docs: update READMEs by @Giuseppe5 in #584

Full Changelog: v0.9.0...v0.9.1