Bump alpine from 3.20.2 to 3.20.3

Bumps alpine from 3.20.2 to 3.20.3.

---
updated-dependencies:
- dependency-name: alpine
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Dockerfile

@@ -1,4 +1,4 @@
-FROM docker.io/alpine:3.20.2
+FROM docker.io/alpine:3.20.3
 
 # https://dovecot.org/doc/NEWS
 # https://git.alpinelinux.org/aports/log/main/dovecot?h=3.20-stable