Resolver: Update the base image.

resolver/Dockerfile

-FROM alpine:3.13
+FROM alpine:3.20
 # hadolint ignore=DL3018
 RUN echo '@testing http://dl-cdn.alpinelinux.org/alpine/edge/testing' >> /etc/apk/repositories && \
     echo '@community http://dl-cdn.alpinelinux.org/alpine/edge/community' >> /etc/apk/repositories && \