package/fetchmail: bump version to 6.4.23

Release notes:
https://sourceforge.net/p/fetchmail/mailman/message/37376434/

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/fetchmail/fetchmail.hash

@@ -1,4 +1,4 @@
-# From https://sourceforge.net/p/fetchmail/mailman/message/37350119/
-sha256  cc6818bd59435602169fa292d6d163d56b21c7f53112829470a3aceabe612c84  fetchmail-6.4.22.tar.xz
+# From https://sourceforge.net/p/fetchmail/mailman/message/37376434/
+sha256  5f7a5e13731431134a2ca535bbced7adc666d3aeb93169a0830945d91f492300  fetchmail-6.4.23.tar.xz
 # Locally computed:
 sha256  001d1b8d111a83e3bab8b4d511ea4767d37d3bd0583560fccece630df1ba8f3c  COPYING

package/fetchmail/fetchmail.mk

@@ -5,7 +5,7 @@
 ################################################################################
 
 FETCHMAIL_VERSION_MAJOR = 6.4
-FETCHMAIL_VERSION = $(FETCHMAIL_VERSION_MAJOR).22
+FETCHMAIL_VERSION = $(FETCHMAIL_VERSION_MAJOR).23
 FETCHMAIL_SOURCE = fetchmail-$(FETCHMAIL_VERSION).tar.xz
 FETCHMAIL_SITE = http://downloads.sourceforge.net/project/fetchmail/branch_$(FETCHMAIL_VERSION_MAJOR)
 FETCHMAIL_LICENSE = GPL-2.0; some exceptions are mentioned in COPYING