* gnu/packages/haskell.scm (ghc-graphviz): Update to 2999.20.0.2. [native-inputs]: Add ghc-hspec, graphviz and hspec-discover.
* gnu/packages/haskell.scm (ghc-graphviz): Update to 2999.20.0.2. [native-inputs]: Add ghc-hspec, graphviz and hspec-discover.