MFH: r533167

Update to 5.3.1

This release contains a security fix for CVE-2020-1747. FullLoader was still
exploitable for arbitrary command execution.
https://bugzilla.redhat.com/show_bug.cgi?id=1807367

Thanks to Riccardo Schirone (https://github.com/ret2libc) for both reporting
this and providing the fixes to resolve it.

• https://github.com/yaml/pyyaml/pull/386

PR: 245937
Submitted by: daniel.engberg.lists@pyret.net
Security: http://vuxml.freebsd.org/freebsd/aae8fecf-888e-11ea-9714-08002718de91.html

Approved by: portmgr (joneum)