Update mainline to Alpine 3.16

mainline/alpine-perl/Dockerfile

@@ -3,7 +3,7 @@
 #
 # PLEASE DO NOT EDIT IT DIRECTLY.
 #
-FROM alpine:3.15
+FROM alpine:3.16
 
 LABEL maintainer="NGINX Docker Maintainers <docker-maint@nginx.com>"
 

mainline/alpine/Dockerfile

@@ -3,7 +3,7 @@
 #
 # PLEASE DO NOT EDIT IT DIRECTLY.
 #
-FROM alpine:3.15
+FROM alpine:3.16
 
 LABEL maintainer="NGINX Docker Maintainers <docker-maint@nginx.com>"
 

update.sh

@@ -35,7 +35,7 @@ declare -A debian=(
 )
 
 declare -A alpine=(
-    [mainline]='3.15'
+    [mainline]='3.16'
     [stable]='3.16'
 )