databases/mongodb34: set deprecated and expiration_date
- Upstream goes EOL in January 2020. See https://www.mongodb.com/support-policy
- There are no dependencies in the ports tree.
- Give people some slack before expiration/removal of the port.
- Newer version of MongoDB have ports and are actively maintained.
PR: 241585
Submitted by: Ronald Klop <ronald-lists@klop.ws> (maintainer)