Update Alpine version to 3.18 (a link to the latest 3.18.x tag)

docker-files/alpine.Dockerfile

@@ -4,11 +4,12 @@
 # https://github.com/nicolargo/glances
 #
 
-# WARNING: the versions should be set.
-# Ex: Python 3.11 for Alpine 3.18
 # Note: ENV is for future running containers. ARG for building your Docker image.
 
-ARG IMAGE_VERSION=3.18.4
+# WARNING: the Alpine image version and Python version should be set.
+# Alpine 3.18 tag is a link to the latest 3.18.x version.
+# Be aware that if you change the Alpine version, you may have to change the Python version.
+ARG IMAGE_VERSION=3.18
 ARG PYTHON_VERSION=3.11
 
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