change: update docker references

.github/workflows/test-matrix.yaml

@@ -37,6 +37,7 @@ jobs:
           - "20.10.5"
           - "20.10.12"
           - "20.10.17"
+          - "23.0.1"
     steps:
       - uses: actions/checkout@v3
       - name: Setup Docker

Dockerfile

@@ -1,4 +1,4 @@
-ARG DOCKER_VERSION=20.10
+ARG DOCKER_VERSION=23.0.1
 ############################################################
 # builder                                                  #
 # -> golang image used solely for building the k3d binary  #

Makefile

@@ -30,7 +30,7 @@ endif
 K3D_IMAGE_TAG := $(GIT_TAG:v%=%)
 
 # get latest k3s version: grep the tag and replace + with - (difference between git and dockerhub tags)
-K3S_TAG		:= $(shell curl --silent --retry 3 "https://update.k3s.io/v1-release/channels/stable" | egrep -o '/v[^ ]+"' | sed -E 's/\/|\"//g' | sed -E 's/\+/\-/')
+K3S_TAG := $(shell curl --silent --retry 3 "https://update.k3s.io/v1-release/channels/stable" | egrep -o '/v[^ ]+"' | sed -E 's/\/|\"//g' | sed -E 's/\+/\-/')
 
 ifeq ($(K3S_TAG),)
 $(warning K3S_TAG undefined: couldn't get latest k3s image tag!)