fix: exclude po files from composer dist

Author: williamdes

.gitattributes

@@ -11,5 +11,6 @@ src/Resources/themes/default/data export-ignore
 .editorconfig export-ignore
 /examples export-ignore
 /locale/Doctum.pot export-ignore
+/locale/*.po export-ignore
 /tests export-ignore
 CHANGELOG.md export-ignore