Release v2.5.0.1

Released with GHC 8.8.1

stm 2.5.0.0

  * Removed `alwaysSucceeds` and `always`, GHC's invariant checking primitives. (GHC #14324)

  * Add `lengthTBQueue` to `Control.Concurrent.STM.TBQueue` (gh-9)

  * Add `stateTVar :: TVar s -> (s -> (a, s)) -> STM a` combinator (gh-14)

  * Switched `newTBQueue` and `newTBQueueIO` to accept `Natural` as size (gh-17)

  * Switched `signalTSemN` and `newTSem` to accept `Natural` and `Integer` respectively (gh-17)

stm 2.4.5.1

* Fix incorrect bookkeeping of write capacity in `flushTBQueue` (gh-9)

* Avoid redundant `writeTVar`s in `flushTQueue` to avoid unncessarily
  invalidating other transactions (gh-6)

stm 2.4.5.0