install gettext for translations

.github/workflows/translations.yml

@@ -26,7 +26,7 @@ jobs:
           wget --quiet https://downloads.crowdin.com/cli/v2/crowdin-cli.zip
           unzip -j crowdin-cli.zip
 
-          sudo apt-get install python2.7
+          sudo apt-get install python2.7 gettext
           python -m pip install --upgrade pip
           python -m pip install flask==0.* jinja2 Babel ./pyembroidery