Merge pull request #160 from erikd/master

Support ghc-9.12

Author: simonmar

async.cabal

@@ -70,7 +70,7 @@ library
         other-extensions: Trustworthy
     exposed-modules:     Control.Concurrent.Async
                          Control.Concurrent.Async.Internal
-    build-depends:       base     >= 4.3     && < 4.21,
+    build-depends:       base     >= 4.3     && < 4.22,
                          hashable >= 1.1.2.0 && < 1.6,
                          stm      >= 2.2     && < 2.6