Move reuse dependency to requirements.txt file (#4547)

.github/dependabot.yml

@@ -14,3 +14,8 @@ updates:
     directory: /tools/serve_header
     schedule:
       interval: daily
+
+  - package-ecosystem: pip
+    directory: /.reuse
+    schedule:
+      interval: daily

.github/workflows/ubuntu.yml

@@ -282,7 +282,7 @@ jobs:
         with:
           python-version: '3.11'
       - name: Install REUSE tool
-        run:  python -m pip install reuse==5.0.2
+        run:  python -m pip install -r .reuse/requirements.txt
       - name: Run REUSE lint
         run: reuse lint