[pkg] Add missing entries to MANIFEST.in
Detected by running `check-manifest
<https://github.com/mgedmin/check-manifest>`_. Add a tox environment
accordingly.
Closes #15229018.
for table, column in [
('transactions', 'tx_time'),
('tx_entity_actions', 'tx_uuid'),
('tx_relation_actions', 'tx_uuid')]:
repo.system_source.create_index(session, table, column)
commit()