v0.13.0: make ONNX dependency optional

What's Changed

This adds a native BLAS backend, keeping the ONNX dependency as an optional backend.
This allows to pin glic to a lower version and resolves #73.

• chore: bump version to 0.12.0+dev by @dacorvo in #71
• doc: add lanscape comparison by @dacorvo in #74
• docs(rationale): mention dismissed experiments by @dacorvo in #75
• Make ONNX dependency optional by @dacorvo in #76

Full Changelog: v0.12.0...v0.13.0