Validator 1.6.5

The core developers have tagged a v1.6.5 mandatory release. Key updates for this release include enabling the return to production of snapshots, garbage collection improvements, and accelerated POC ledger items.

This release also includes updates from earlier v1.6.x releases.

Before updating to v1.6.5 the team recommends source builders upgrade to rust 1.58. Directly updating to v1.6.5 from earlier v1.6.x versions is supported.

Shout out to @PaulVMo for his research and pull request #1367.