chore: update dependencies and bump version to 0.8.0

[hexcowboy]

What changed

• Updated every direct runtime and development dependency to its latest crates.io release.
• Migrated Redis runtime feature wiring from async-std-rustls-comp to smol-rustls-comp for Redis 1.x while preserving rslock's existing async-std-comp feature name.
• Updated the Rand 0.10 trait imports.
• Cleaned up test and example patterns flagged by the current Clippy release.
• Bumped rslock from 0.7.4 to 0.8.0.

Why

Several dependencies had newer major or minor releases available, including Redis 1.x, Rand 0.10, and Testcontainers 0.27. Because Redis types appear in rslock's public API, the Redis major upgrade can affect downstream compatibility. The project's documented pre-1.0 semver policy therefore calls for a minor release bump.

Impact

Consumers receive current dependency versions and should review Redis 1.x compatibility when upgrading to rslock 0.8.0. The public rslock feature name remains unchanged.

Validation

• cargo fmt --check
• cargo clippy --locked --all-features --all-targets -- -D warnings
• cargo test --locked --all-features --all-targets (27 passed)