package/fetchmail: security bump version to 6.4.20

Fixes CVE-2021-36386:
https://sourceforge.net/p/fetchmail/mailman/message/37327393/

Release notes:
https://sourceforge.net/p/fetchmail/mailman/message/37327392/

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/fetchmail/fetchmail.hash

@@ -1,6 +1,6 @@
-# From https://sourceforge.net/p/fetchmail/mailman/message/37267719/
-sha256  cd8d11a3d103e50caa2ec64bcda6307eb3d0783a4d4dfd88e668b81aaf9d6b5f  fetchmail-6.4.19.tar.xz
+# From https://sourceforge.net/p/fetchmail/mailman/message/37327392/
+sha256  c82141ae2e8f0039ceb0c5c2eda43c5e93ad0bf7f9c6bb628092b3be74386176  fetchmail-6.4.20.tar.xz
 # From https://sourceforge.net/projects/fetchmail/files/branch_6.4/
-sha1  bb6959f0cf1f6d689c2ba3834c5bba72e4f9ec07  fetchmail-6.4.19.tar.xz
+sha1  ac6a6c4afa105e097d025340cf78b32e0c3b0c8e  fetchmail-6.4.20.tar.xz
 # Locally computed:
 sha256  6346b5aa04e258fa4326272ea92372d796b4382aa963535ae98a3bb5f8cd5aeb  COPYING

package/fetchmail/fetchmail.mk

@@ -5,7 +5,7 @@
 ################################################################################
 
 FETCHMAIL_VERSION_MAJOR = 6.4
-FETCHMAIL_VERSION = $(FETCHMAIL_VERSION_MAJOR).19
+FETCHMAIL_VERSION = $(FETCHMAIL_VERSION_MAJOR).20
 FETCHMAIL_SOURCE = fetchmail-$(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