Upgrade base docker image to Ubuntu 20.04.

.github/workflows/docker.yml

@@ -25,7 +25,7 @@ jobs:
         run: |
           docker buildx build \
             --tag berthubert/galmon \
-            --platform linux/386,linux/amd64,linux/arm/v7,linux/arm64/v8 \
+            --platform linux/amd64,linux/arm/v7,linux/arm64/v8 \
             --output "type=registry" \
             --build-arg MAKE_FLAGS=-j1 \
             --file Dockerfile \

Dockerfile

@@ -1,7 +1,7 @@
 #
 # First stage - builder
 #
-FROM ubuntu:eoan AS builder
+FROM ubuntu:focal AS builder
 
 ENV DEBIAN_FRONTEND noninteractive
 ENV LC_ALL C.UTF-8
@@ -28,7 +28,7 @@ RUN prefix=/galmon make install
 #
 # Second stage - contains just the binaries
 #
-FROM ubuntu:eoan
+FROM ubuntu:focal
 RUN apt-get update && apt-get -y upgrade \
     && apt-get install -y libh2o0.13 libcurl4 libssl1.1 libprotobuf17 \
            libh2o-evloop0.13 libwslay1 libzstd1 \