ensure copyright is mode 644

resolves non-standard-file-perm
https://lintian.debian.org/tags/non-standard-file-perm.html

.github/workflows/CICD.yml

@@ -359,6 +359,7 @@ jobs:
          IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
          DEALINGS IN THE SOFTWARE.
         EOF
+          chmod 644 "${DPKG_DIR}/usr/share/doc/${{ env.PROJECT_NAME }}/copyright"
 
           # control file
           mkdir -p "${DPKG_DIR}/DEBIAN"