net-mgmt/cacti: Update to 1.2.17

Full changelog: https://github.com/Cacti/cacti/releases/tag/release%2F1.2.17

PR: 256325
Security: CVE-2020-35701
MFH: 2021Q2
Approved by: Michael Muenz <m.muenz@gmail.com> (maintainer)

(cherry picked from commit 073124bd04f0d5cb9c80599da3df15887e3968ef)