QA: Bump github.com/go-git/go-git/v5 from 5.19.1 to 5.19.2

## Dependabot dependency update — QA review needed | Field | Value | |-------|-------| | **PR** | #50787 | | **Ecosystem** | Go | | **Branch** | `dependabot-go_modules-github.com-go-git-go-git-v5-5.19.2` | ### Why this needs QA Dependabot PRs update third-party dependencies. Even minor/patch bumps can change runtime behavior (see #45763 for a real example where a dependency bump silently broke SCEP certificate issuance). Please verify that the updated dependency does not cause regressions in related functionality. ### What to check 1. Review the PR diff and the dependency's changelog/release notes 2. Identify which Fleet features use this dependency 3. Test those features for behavioral changes --- *This issue was automatically created by the dependabot-qa-ticket workflow.*