git subrepo pull (merge) mailcow/src/mailcow-dockerized

Among other things, this updates Dovecot to 2.3.13, which is a
critical security update.

subrepo: subdir:   "mailcow/src/mailcow-dockerized"
  merged:   "376574d9"
upstream: origin:   "https://github.com/mailcow/mailcow-dockerized.git"
  branch:   "master"
  commit:   "6f14955b"
git-subrepo: version:  "0.4.3"
  origin:   "???"
  commit:   "???"
Change-Id: Idf4859ddaaebf6997afbb0cebffc8bf3f5b902a0
diff --git a/mailcow/src/mailcow-dockerized/docker-compose.yml b/mailcow/src/mailcow-dockerized/docker-compose.yml
index 5362bfc..a1cb21a 100644
--- a/mailcow/src/mailcow-dockerized/docker-compose.yml
+++ b/mailcow/src/mailcow-dockerized/docker-compose.yml
@@ -194,7 +194,7 @@
             - sogo
 
     dovecot-mailcow:
-      image: mailcow/dovecot:1.138
+      image: mailcow/dovecot:1.139
       depends_on:
         - mysql-mailcow
       dns: