CI: enable REUSE

Author: ForNeVeR

.github/workflows/main.yml

@@ -19,3 +19,12 @@ jobs:
       - name: Verify encoding
         shell: pwsh
         run: Install-Module VerifyEncoding -Repository PSGallery -RequiredVersion 2.2.0 -Force && Test-Encoding
+
+  licenses:
+    runs-on: ubuntu-24.04
+    steps:
+      - name: Check out the repository
+        uses: actions/checkout@v4
+
+      - name: REUSE license check
+        uses: fsfe/reuse-action@v5