Update Hugo to version 0.56.0

Dockerfile

@@ -9,9 +9,9 @@
 # to work around segmentation fault issues.
 FROM golang:1.12-alpine
 ARG HUGO=hugo
-ARG HUGO_VERSION=0.55.6
-ARG HUGO_SHA=39d3119cdb9ba5d6f1f1b43693e707937ce851791a2ea8d28003f49927c428f4
-ARG HUGO_EXTENDED_SHA=8962b8cdc0ca220da97293cea0bb1b31718cb4d99d0766be6865cb976b1c1805
+ARG HUGO_VERSION=0.56.0
+ARG HUGO_SHA=f70a79d27fc5a93469c9e3cf9f2385e46e0140fe5708bab667caed8e22fd7912
+ARG HUGO_EXTENDED_SHA=687f9913f1f104badb713d22de45e8cb75b83f5114dddb581b9c8b82babe2d0d
 RUN set -eux && \
     case ${HUGO} in \
       *_extended) \