Release 1.2.3

Contains only a minor fix for 1.2.2, addressing an issue where a node could lose its
reference to a remote node via expired actor pruning, but not be able to recover.

Fixes
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ba7727e Don't remove MembershipRoundTrip entry on expire
7df7226 Add liveness entry on resolution
Merge pull request #102 from clinedome-work/release-1.2.3

Release 1.2.3