Update Hugo to version 0.64.1

Dockerfile

@@ -9,9 +9,9 @@
 # to work around segmentation fault issues.
 FROM golang:1.13-alpine
 ARG HUGO=hugo
-ARG HUGO_VERSION=0.64.0
-ARG HUGO_SHA=99c4752bd46c72154ec45336befdf30c28e6a570c3ae7cc237375cf116cba1f8
-ARG HUGO_EXTENDED_SHA=f023333932fa3073f1e0ad73281b3e0ecd0fd0b3f3054eb353e82d64120f59d2
+ARG HUGO_VERSION=0.64.1
+ARG HUGO_SHA=5c5573be0bf4113b280c4674eba0aff62224c4b076c9ef7c2e626cbd29f5b439
+ARG HUGO_EXTENDED_SHA=a5276d78881561a9873fe92531c3c815758b4a3f42fac9b7bbb2f962107da68f
 RUN set -eux && \
     case ${HUGO} in \
       *_extended) \