Fix min bound for ghc-exactprint dependency (#2710)

Author: pepeiborra

plugins/hls-class-plugin/hls-class-plugin.cabal

@@ -28,7 +28,7 @@ library
     , base            >=4.12 && <5
     , containers
     , ghc
-    , ghc-exactprint
+    , ghc-exactprint  >= 0.6.4
     , ghcide          ^>=1.6
     , hls-plugin-api  ^>=1.3
     , lens