fix: translation only applied on app start

* the problem was that with gettext the translations for column labels
  have been only be calculated on boot time.

* using lazy_gettext instead fixes that, because it calculates
  the translation at the request level

Co-authored-by: Mirek Simek <[email protected]>

invenio_records/admin.py

@@ -15,7 +15,7 @@
 from flask_admin.contrib.sqla import ModelView
 from invenio_admin.filters import FilterConverter
 from invenio_db import db
-from invenio_i18n import gettext as _
+from invenio_i18n import lazy_gettext as _
 from markupsafe import Markup
 from sqlalchemy.exc import SQLAlchemyError