Bump alpine from 3.17.2 to 3.17.3 (#51)

Dockerfile

@@ -1,4 +1,4 @@
-FROM docker.io/alpine:3.17.2
+FROM docker.io/alpine:3.17.3
 
 ARG DOVECOT_PACKAGE_VERSION=2.3.20-r7
 ARG SOCAT_PACKAGE_VERSION=1.7.4.4-r0