Fixes ElementsProject#5276 by using as docker base image debian bullseye instead of buster

Changelog-Fixed: Upgrade docker base image from Debian buster to bullseye to work with glibc 2.29+ ElementsProject#5276

Author: Jossec101

Dockerfile

@@ -5,7 +5,7 @@
 # * final: Copy the binaries required at runtime
 # The resulting image uploaded to dockerhub will only contain what is needed for runtime.
 # From the root of the repository, run "docker build -t yourimage:yourtag ."
-FROM debian:buster-slim as downloader
+FROM debian:bullseye-slim as downloader
 
 RUN set -ex \
 	&& apt-get update \
@@ -45,7 +45,7 @@ RUN mkdir /opt/litecoin && cd /opt/litecoin \
     && tar -xzvf litecoin.tar.gz $BD/litecoin-cli --strip-components=1 --exclude=*-qt \
     && rm litecoin.tar.gz
 
-FROM debian:buster-slim as builder
+FROM debian:bullseye-slim as builder
 
 ENV LIGHTNINGD_VERSION=master
 RUN apt-get update -qq && \
@@ -111,7 +111,7 @@ RUN curl -sSL https://raw.githubusercontent.com/python-poetry/poetry/master/inst
 
 RUN ./configure --prefix=/tmp/lightning_install --enable-static && make -j3 DEVELOPER=${DEVELOPER} && make install
 
-FROM debian:buster-slim as final
+FROM debian:bullseye-slim as final
 
 COPY --from=downloader /opt/tini /usr/bin/tini
 RUN apt-get update && apt-get install -y --no-install-recommends socat inotify-tools python3 python3-pip libpq5\