[CI] Bump obi1kenobi/cargo-semver-checks-action from 2.6 to 2.8 (#2827)

Bumps [obi1kenobi/cargo-semver-checks-action](https://github.com/obi1kenobi/cargo-semver-checks-action) from 2.6 to 2.8.
- [Release notes](https://github.com/obi1kenobi/cargo-semver-checks-action/releases)
- [Commits](obi1kenobi/cargo-semver-checks-action@7272cc2...5b298c9)

---
updated-dependencies:
- dependency-name: obi1kenobi/cargo-semver-checks-action
  dependency-version: '2.8'
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -572,7 +572,7 @@ jobs:
     # gets run on different targets. Some of our API is target-specific (e.g.,
     # SIMD type impls), and so we need to run on each target.
     - name: Check semver compatibility
-      uses: obi1kenobi/cargo-semver-checks-action@7272cc2caa468d3e009a2b0a9cc366839348237b # v2.6
+      uses: obi1kenobi/cargo-semver-checks-action@5b298c9520f7096a4683c0bd981a7ac5a7e249ae # v2.8
       with:
         # Don't semver check zerocopy-derive; as a proc macro, it doesn't have
         # an API that cargo-semver-checks can understand.