Log Message:
xfce4-exo: update to 0.12.8

Change log:

0.12.8
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- preferred-apps: Add button icons to Help/Close
- Replace GtkStock buttons
- Translation Updates:
  Czech, Galician, Portuguese (Brazil)

0.12.7
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- Translation Updates: Armenian, Armenian (Armenia), Danish,
  Finnish, Hebrew, Indonesian, Italian, Kazakh, Norwegian Bokmål,
  Serbian, Ukrainian