linux/Dockerfile: upgrade to alpine 3.11

Closes: #6180

linux/Dockerfile

@@ -1,14 +1,21 @@
 # USE ALPINE LINUX
-FROM alpine:3.10
-RUN apk update
-RUN apk add alpine-sdk git ca-certificates ghc gmp-dev zlib-dev bash dpkg fakeroot cabal
-RUN mkdir -p /usr/src/
-WORKDIR /usr/src/
-RUN git clone https://github.com/jgm/pandoc
+FROM alpine:3.11
+RUN apk --no-cache add \
+      alpine-sdk \
+      bash \
+      ca-certificates \
+      cabal \
+      dpkg \
+      fakeroot \
+      ghc \
+      git \
+      gmp-dev \
+      xz \
+      zlib-dev \
+      zlib-static
+RUN mkdir -p /usr/src/ && \
+    git clone https://github.com/jgm/pandoc /usr/src/pandoc
 WORKDIR /usr/src/pandoc
-RUN cabal update && \
-    cabal install cabal-install-2.4.0.0 && \
-    cp $HOME/.cabal/bin/cabal /usr/bin/
 CMD cabal --version && \
     ghc --version && \
     git pull && \