devel/mongo-c-driver: Update 2.3.3 => 2.5.6

Changelogs:
https://github.com/mongodb/mongo-c-driver/releases/tag/2.4.0
https://github.com/mongodb/mongo-c-driver/releases/tag/2.5.0
https://github.com/mongodb/mongo-c-driver/releases/tag/2.5.1
https://github.com/mongodb/mongo-c-driver/releases/tag/2.5.2
https://github.com/mongodb/mongo-c-driver/releases/tag/2.5.3
https://github.com/mongodb/mongo-c-driver/releases/tag/2.5.4
https://github.com/mongodb/mongo-c-driver/releases/tag/2.5.5
https://github.com/mongodb/mongo-c-driver/releases/tag/2.5.6

PR: 299416
Sponsored by: UNIS Labs (vvd, commit patch)
MFH: 2026Q4