lang/python35: Fix security issues

The patches for CVE-2019-18348 and CVE-2020-8492 are in the 3.5 branch
and will be present in a next release.

PR: 246984
Approved by: python (with hat)
MFH: 2020Q2
Security: ca595a25-91d8-11ea-b470-080027846a02 (CVE-2019-18348)
Security: a27b0bb6-84fc-11ea-b5b4-641c67a117d8 (CVE-2020-8492)