Log Message:
(net/p5-Net-DNS) Updated to 1.21

**** 1.21 Aug 30, 2019
 - Fix error report for non-existent or recursive zone file $INCLUDE.
 - Emit one deprecation warning on invocation of obsolete method.
 - Rework OPT.pm EDNS0 option construction.
 - Remove obsolete Net::DNS::RR::DLV package.
 - Add Net::DNS::RR::ZONEMD package.

Fix rt.cpan.org #128901
        background TCP query logic expects to read entire response at once