Update stable to Alpine 3.20

stable/alpine-slim/Dockerfile

@@ -3,7 +3,7 @@
 #
 # PLEASE DO NOT EDIT IT DIRECTLY.
 #
-FROM alpine:3.19
+FROM alpine:3.20
 
 LABEL maintainer="NGINX Docker Maintainers <docker-maint@nginx.com>"
 

update.sh

@@ -56,7 +56,7 @@ declare -A debian=(
 
 declare -A alpine=(
     [mainline]='3.20'
-    [stable]='3.19'
+    [stable]='3.20'
 )
 
 # When we bump njs version in a stable release we don't move the tag in the