fix: add gcompat to the alpine image to fix libc (#107)

Reviewed-on: docker/hugo#107

Dockerfile

@@ -17,7 +17,7 @@ ENV HUGO_ENV=production
 COPY overlay/ /
 
 RUN apk add --update --no-cache --virtual .build-deps tar curl && \
-    apk add --update --no-cache libc6-compat libstdc++ busybox-suid bash bash-completion git tzdata make asciidoctor && \
+    apk add --update --no-cache gcompat libc6-compat libstdc++ busybox-suid bash bash-completion git tzdata make asciidoctor && \
     echo "Installing hugo version '${HUGO_VERSION##v}' ..." && \
     curl -SsfL "https://github.com/gohugoio/hugo/releases/download/${HUGO_VERSION}/hugo_extended_${HUGO_VERSION##v}_Linux-64bit.tar.gz" | \
       tar xz -C /usr/local/bin hugo && \