message: Fix ghc ppa path
diff: @@ -54,7 +54,7 @@ RUN add-apt-repository ppa:cwchien/gradle && \
  openjdk-8-jdk-headless
  # Components for ghc
  -RUN add-apt-repository ppa:hvr\ghc -y && \
  +RUN add-apt-repository ppa:hvr/ghc -y && \
  apt-get update && \
  apt-get -y install ghc-8.6.5
  