Rename to rustac

[gadomski]

This is an implementation-tracking ticket for our rename to rustac (RFC). We're aiming to have this done by end of March 2025 at the latest, and maybe much sooner.

• Socialize RFC on Gitter, Bluesky: https://bsky.app/profile/gadom.ski/post/3lj3ij2w5ns2e
• Squat https://pypi.org/project/rustac/
• Rename this repo to rustac: refactor: s/stac-rs/rustac/ #696
• Rename https://github.com/stac-utils/stacrs to rustac-py
• Publish new breaking version of rustac-py (since we're changing the package name there to rustac)
• Yank the squat release
• Announce change
  • Discussions (here): Rename to rustac #706
  • Discussions (https://github.com/radiantearth/stac-spec/discussions/categories/stac-software): rustac: the power of Rust for the STAC ecosystem radiantearth/stac-spec#1339
  • Gitter
  • BlueSky: https://bsky.app/profile/gadom.ski/post/3ln3xgdyy522x
• Close [RFC] Rename this repo to rustac, update ecosystem accordingly #641