dev-perl/MongoDB: Bump to version 1.6.0

dev-perl/MongoDB: Bump to version 1.6.0

Upstream:
- MongoDB::GridFS{,::FIle} deprecated
- Add support for maxTimeMS in parallel_scan
- Add MongoDB::GridFSBucket for new GridFS API
- Database->collection_names takes a filter parameter
- Add support for custom file_id values for GridFS files
- Add support for maxStalenessSeconds
- Add support for Decimal128 BSON
- Add support for sending write concern for all allowable
  database commands
- Add support for collations with CRUD/Indexing
- Report client information to server during handshake

Package-Manager: portage-2.3.2