Prepare 2.4.5.1 release

changelog.md

 # Changelog for [`stm` package](http://hackage.haskell.org/package/stm)
 
+## 2.4.5.1 *Sep 2018*
+
+  * Fix incorrect bookkeeping of write capacity in `flushTBQueue` (gh-9)
+
+  * Avoid redundant `writeTVar`s in `flushTQueue` to avoid unncessarily
+    invalidating other transactions (gh-6)
+
 ## 2.4.5.0 *Feb 2018*
 
   * Fix space leak in `TBQueue` (gh-2, GHC#14494)

stm.cabal

+cabal-version:  >=1.10
 name:           stm
-version:        2.4.5.0
--- don't forget to update changelog.md file!
+version:        2.4.5.1
+-- don't forget to update changelog.md file & source-repo tag!
+
 license:        BSD3
 license-file:   LICENSE
 maintainer:     libraries@haskell.org
@@ -9,7 +11,6 @@ bug-reports:    https://github.com/haskell/stm/issues
 synopsis:       Software Transactional Memory
 category:       Concurrency
 build-type:     Simple
-cabal-version:  >=1.10
 tested-with:    GHC==7.10.*, GHC==7.8.*, GHC==7.6.*, GHC==7.4.*, GHC==7.2.*, GHC==7.0.*
 description:
     Software Transactional Memory, or STM, is an abstraction for
@@ -28,6 +29,11 @@ source-repository head
     type:     git
     location: https://github.com/haskell/stm.git
 
+source-repository this
+    type:     git
+    location: https://github.com/haskell/stm.git
+    tag:      v2.4.5.1
+
 library
     default-language: Haskell2010
     other-extensions: