main/gnupg: fix secfix CVE-2020-25125 assigned to wrong pkgver

Introduced in b70c9119

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-25125

main/gnupg/APKBUILD

@@ -70,7 +70,7 @@ source="https://gnupg.org/ftp/gcrypt/gnupg/gnupg-$_ver.tar.bz2
 	"
 
 # secfixes:
-#   2.2.13-r0:
+#   2.2.23-r0:
 #     - CVE-2020-25125
 #   2.2.18-r0:
 #     - CVE-2019-14855