automation: upgrade Alpine build and test artifact containers to 3.18

Alpine 3.12 is EOL. Also update the containerize script.

Signed-off-by: Stefano Stabellini <stefano.stabellini@amd.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>

automation/build/alpine/3.18-arm64v8.dockerfile

@@ -1,4 +1,4 @@
-FROM arm64v8/alpine:3.12
+FROM arm64v8/alpine:3.18
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
 

automation/build/alpine/3.18.dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.12
+FROM alpine:3.18
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
 

automation/scripts/containerize

@@ -24,8 +24,8 @@ die() {
 #
 BASE="registry.gitlab.com/xen-project/xen"
 case "_${CONTAINER}" in
-    _alpine) CONTAINER="${BASE}/alpine:3.12" ;;
+    _alpine) CONTAINER="${BASE}/alpine:3.18" ;;
-    _alpine-arm64v8) CONTAINER="${BASE}/alpine:3.12-arm64v8" ;;
+    _alpine-arm64v8) CONTAINER="${BASE}/alpine:3.18-arm64v8" ;;
     _archlinux|_arch) CONTAINER="${BASE}/archlinux:current" ;;
     _riscv64) CONTAINER="${BASE}/archlinux:current-riscv64" ;;
     _centos7) CONTAINER="${BASE}/centos:7" ;;

automation/tests-artifacts/alpine/3.18-arm64v8.dockerfile

@@ -1,4 +1,4 @@
-FROM arm64v8/alpine:3.12
+FROM arm64v8/alpine:3.18
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
 
@@ -18,7 +18,7 @@ RUN \
   apk add sudo && \
   apk add dbus && \
   apk add bash && \
-  apk add python2 && \
+  apk add python3 && \
   apk add zlib && \
   apk add ncurses && \
   apk add texinfo && \

automation/tests-artifacts/alpine/3.18.dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.12
+FROM alpine:3.18
 LABEL maintainer.name="The Xen Project" \
       maintainer.email="xen-devel@lists.xenproject.org"
 
@@ -19,7 +19,7 @@ RUN \
   apk add sudo && \
   apk add dbus && \
   apk add bash && \
-  apk add python2 && \
+  apk add python3 && \
   apk add zlib && \
   apk add ncurses && \
   apk add texinfo && \