Update base image to alpine 3.19

[bmillemathias]

3.16 security support ends May 23rd 2024

Tested doing a basic test from my laptop to relay a mail to my smtp upstream server

➜  telnet 127.0.0.1 2525
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
220 scamorza.doesnotexists.fr ESMTP Postfix
EHLO dsdsd.cf
250-scamorza.alcmeon.com
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250-DSN
250 CHUNKING
MAIL FROM: me@doesnotexists.fr
250 2.1.0 Ok
RCPT TO: baptistemm@heya.com 
250 2.1.5 Ok
DATA
354 End data with <CR><LF>.<CR><LF>
From: me@doesnotexists.fr
To: baptistemm@heya.com 
Subject: Telnet email

Testing I can connect to a local smtp server
.
250 2.0.0 Ok: queued as DC9D14A500D3

[djjudas21]

Sorry, I wasn't ignoring you, for some reason I didn't get a notification of this PR. I'm happy with it, will merge now.

[bmm-alc]

Sorry, I wasn't ignoring you, for some reason I didn't get a notification of this PR. I'm happy with it, will merge now.

no problems :)

[djjudas21]

Merged in b30b20f