debian: correctly regenerate copyright file (arduino#2979)

* debian: correctly regenerate copyright file

* ci: add check

Author: alessio-perugini

.github/workflows/check-go-dependencies-task.yml

@@ -139,3 +139,8 @@ jobs:
 
       - name: Check for dependencies with unapproved licenses
         run: task --silent general:check-dep-licenses
+
+      - name: Check debian copyright file
+        run: |
+          task update-deb-copyright
+          git diff --color --exit-code