gnu: Dovecot: Update to 2.3.7.2 [fixes CVE-2019-11500].

* gnu/packages/mail.scm (dovecot): Update to 2.3.7.2.

gnu/packages/mail.scm

@@ -1285,7 +1285,7 @@ facilities for checking incoming mail.")
 (define-public dovecot
   (package
     (name "dovecot")
-    (version "2.3.6")
+    (version "2.3.7.2")
     (source
      (origin
        (method url-fetch)
@@ -1293,7 +1293,8 @@ facilities for checking incoming mail.")
                            (version-major+minor version) "/"
                            "dovecot-" version ".tar.gz"))
        (sha256
-        (base32 "1irnalplb47nlc26dn7zzdi95zhrxxi3miza7p3wdsgapv0qs7gd"))))
+        (base32
+         "0q0jgcv3ni2znkgyhc966ffphj1wk73y76wssh0yciqafs2f0v36"))))
     (build-system gnu-build-system)
     (native-inputs
      `(("pkg-config" ,pkg-config)))