deps(ci): bump fsfe/reuse-action from 5 to 6 (#144)

Bumps [fsfe/reuse-action](https://github.com/fsfe/reuse-action) from 5 to 6.
- [Release notes](https://github.com/fsfe/reuse-action/releases)
- [Commits](fsfe/reuse-action@v5...v6)

---
updated-dependencies:
- dependency-name: fsfe/reuse-action
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/reusable-ci.yml

@@ -55,7 +55,7 @@ jobs:
         run: cargo +nightly-2025-08-01 fmt --all -- --check
 
       - name: REUSE Compliance
-        uses: fsfe/reuse-action@v5
+        uses: fsfe/reuse-action@v6
 
   # 🔍 Linting
   clippy: