package/dovecot: bump version to 2.2.28

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
(cherry picked from commit 87b60b2586b44f81ada7e57768ca5dded612ffdc)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/dovecot/dovecot.hash

@@ -1,2 +1,2 @@
 # Locally computed after checking signature
-sha256 897f92a87cda4b27b243f8149ce0ba7b7e71a2be8fb7994eb0a025e54cde18e9  dovecot-2.2.27.tar.gz
+sha256 e0288f59e326ab87cb3881fdabadafe542f4dc7ab9996db13863a439ebbc1f25  dovecot-2.2.28.tar.gz

package/dovecot/dovecot.mk

@@ -5,7 +5,7 @@
 ################################################################################
 
 DOVECOT_VERSION_MAJOR = 2.2
-DOVECOT_VERSION = $(DOVECOT_VERSION_MAJOR).27
+DOVECOT_VERSION = $(DOVECOT_VERSION_MAJOR).28
 DOVECOT_SITE = http://www.dovecot.org/releases/$(DOVECOT_VERSION_MAJOR)
 DOVECOT_INSTALL_STAGING = YES
 DOVECOT_LICENSE = LGPLv2.1