Update fsfe/reuse-action action to v6

Author: renovate[bot]

.github/workflows/reuse.yaml

@@ -12,4 +12,4 @@ jobs:
     steps:
     - uses: actions/checkout@v4
     - name: REUSE Compliance Check
-      uses: fsfe/reuse-action@v5
+      uses: fsfe/reuse-action@v6