build(deps): bump alpine from 3.16.2 to 3.16.3 (#40)

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.16.2
+FROM alpine:3.16.3
 
 ARG POSTFIX_PACKAGE_VERSION=3.7.3-r0
 # http://www.postfix.org/postconf.5.html#tls_append_default_CA