ci: the msrv leg checks the committed Cargo.lock - #88

Process completed with exit code 1.

[Unreleased] carries entries, but the crate version (1.0.0) does not exceed the last release (1.0.0); bump the version in Cargo.toml

Process completed with exit code 1.

the crate version (1.0.0-rc1) is a pre-release, but [Unreleased] carries feature content (### Added, ### Removed, or a **Breaking entry); feature work resets the version to the next regular release

Process completed with exit code 1.

[Unreleased] carries entries, but the crate version (1.0.0-rc1) does not exceed the last release (1.0.0); bump the version in Cargo.toml

Process completed with exit code 1.

no [Unreleased] section to cut in CHANGELOG.md

Process completed with exit code 1.

[Unreleased] marks a breaking change; 0.1.1 over 0.1.0 needs at least a minor bump (0.x) or a major bump (1.x and up)

Process completed with exit code 1.

[Unreleased] carries entries, but the crate version (0.1.0) does not exceed the last release (0.1.0); bump the version in Cargo.toml