(stable) Bump the markup cache version for URI changes

Summary:
Ref T13250. Ref T13249. Some remarkup rules, including {image ...} and {meme ...}, may cache URIs as objects because the remarkup cache is serialize()-based.

URI objects with query cached as a key-value map are no longer valid and can raise __toString() fatals.

Bump the cache version to purge them out of the cache.

Test Plan: See PHI1074.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13250, T13249

Differential Revision: https://secure.phabricator.com/D20160