fix: --version now reports git tag instead of hardcoded 0.1.0

[rafael-graunke]

Closes #208

Root cause

--version was reading CARGO_PKG_VERSION, which is hardcoded to 0.1.0 in Cargo.toml and never updated on releases.

Fix

Switch to VERGEN_GIT_DESCRIBE, which is already generated by vergen-gix during the build and reflects the actual git tag.

Two additional issues had to be addressed to make this work:

1. GixBuilder::all_git() calls .describe(false, false, None) internally, where the first argument means "annotated tags only". This repo uses lightweight tags, so git describe found nothing and emitted an empty string. Fixed by calling .all().describe(true, false, None) to include all tags.
2. actions/checkout@v4 defaults to a shallow clone with no tags. Added fetch-tags: true to both checkout steps so tags are visible during CI builds.

Result

On a tagged commit: mavlink-server 0.8.0
Between releases: mavlink-server 0.8.0-16-gbfc96df

[joaoantoniocardoso]

Hi, welcome!

The changes are good; Before merging, I'll ask you to change the commits to follow the repository pattern.

Your single commit touches 3 different parts of the code, so make it three commits. Here's an example:

ci: Fetch git tags in checkout action

<short reasoning why this is needed>

Then, the other two would be something like build: <short description> and src: lib: cli: <short description>. Feel free to add more context in the commit bodies, similar to what you did in the PR body.

Thanks for the contribution!

[joaoantoniocardoso]

thanks!