chore: Release packages

[github-actions]

🤖 New release

• pumpkin-checking: 0.5.0 -> 0.6.0
• pumpkin-core: 0.5.0 -> 0.6.0 (⚠ API breaking changes)
• pumpkin-conflict-resolvers: 0.5.0 -> 0.6.0 (✓ API compatible changes)
• pumpkin-propagators: 0.5.0 -> 0.6.0 (✓ API compatible changes)
• pumpkin-constraints: 0.5.0 -> 0.6.0
• pumpkin-solver: 0.5.0 -> 0.6.0 (✓ API compatible changes)
• pumpkin-checker: 0.5.0 -> 0.6.0

⚠ pumpkin-core breaking changes

--- failure enum_variant_added: enum variant added on exhaustive enum ---

Description:
A publicly-visible enum without #[non_exhaustive] has a new variant.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#enum-variant-new
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.48.0/src/lints/enum_variant_added.ron

Failed in:
  variant Priority:UltraLow in /tmp/.tmproHoXp/Pumpkin/pumpkin-crates/core/src/propagation/propagator.rs:255
  variant Priority:Lowest in /tmp/.tmproHoXp/Pumpkin/pumpkin-crates/core/src/propagation/propagator.rs:256

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This PR was generated with release-plz.