v0.3.1

Changed

• Widen the replicant requirement from ~> 0.1.0 to ~> 0.3 so consumers can adopt the
  current replicant line (0.3.x) without a resolver conflict. ash_replicant calls only
  replicant's stable core (Replicant.{Change, SchemaChange, Sink, Transaction, lsn},
  Replicant.start_link/1, Replicant.stop/1); verified compatible against replicant 0.3.1:
  mix compile --warnings-as-errors clean and mix test 90 passed / 0 failed (unit suite;
  the :integration gate — 52 tests needing a live wal_level=logical DB via
  ASH_REPLICANT_TEST_URL — is owed in CI before publish). No API or behavior change.