upgrade postfix package from v3.8.3-r1 to v3.8.4-r0 (smtp smuggling)

https://web.archive.org/web/20231231085914/https://www.postfix.org/smtp-smuggling.html
https://web.archive.org/web/20231231085928/https://www.postfix.org/announcements/postfix-3.8.4.html
https://web.archive.org/web/20231231085933/https://git.alpinelinux.org/aports/commit/main/postfix?h=3.19-stable&id=92edea4675da295ce3a10b20f4143bb778c183ef

Dockerfile

@@ -2,7 +2,7 @@ FROM docker.io/alpine:3.19.0
 
 # http://www.postfix.org/announcements.html
 # https://git.alpinelinux.org/aports/log/main/postfix?h=3.19-stable
-ARG POSTFIX_PACKAGE_VERSION=3.8.3-r1
+ARG POSTFIX_PACKAGE_VERSION=3.8.4-r0
 # http://www.postfix.org/postconf.5.html#tls_append_default_CA
 # https://www.mozilla.org/en-US/about/governance/policies/security-group/certs/
 # https://gitlab.alpinelinux.org/alpine/ca-certificates/-/commits/master