chore(CI): Add reuse workflow

Signed-off-by: Joas Schilling <coding@schilljs.com>

.github/workflows/reuse.yml

@@ -0,0 +1,20 @@
+# This workflow is provided via the organization template repository
+#
+# https://github.com/nextcloud/.github
+# https://docs.github.com/en/actions/learn-github-actions/sharing-workflows-with-your-organization
+
+# SPDX-FileCopyrightText: 2022 Free Software Foundation Europe e.V. <https://fsfe.org>
+#
+# SPDX-License-Identifier: CC0-1.0
+
+name: REUSE Compliance Check
+
+on: [push, pull_request]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@0ad4b8fadaa221de15dcec353f45205ec38ea70b # v4.1.4
+      - name: REUSE Compliance Check
+        uses: fsfe/reuse-action@a46482ca367aef4454a87620aa37c2be4b2f8106 # v3.0.0