Bump up hls-plugin-api version

Author: jneira

hls-plugin-api/hls-plugin-api.cabal

@@ -1,6 +1,6 @@
 cabal-version: 2.2
 name:          hls-plugin-api
-version:       0.5.0.1
+version:       0.6.0.0
 synopsis:      Haskell Language Server API for plugin communication
 description:
   Please see the README on GitHub at <https://github.com/haskell/haskell-language-server#readme>