chore: Translate pressbooks-multi-institution.pot in fr

77% of minimum 25% translated source file: 'pressbooks-multi-institution.pot'
on 'fr'.

Sync of partially translated files: 
untranslated content is included with an empty translation 
or source language content depending on file format

languages/pressbooks-multi-institution-fr_FR.po

@@ -191,7 +191,7 @@ msgstr ""
 
 #: src/Support/BookList.php:115
 msgid "There are %d books owned by %s. They use %s of storage."
-msgstr ""
+msgstr "Il y a %d livres possédés par %s. Ils utilisent %s de stockage."
 
 #: src/Views/AssignBooksTable.php:33
 msgid "Cover"