[3.18] community/arti: upgrade to 1.1.5

https://gitlab.torproject.org/tpo/core/arti/-/blob/arti-v1.1.5/CHANGELOG.md?ref_type=tags#arti-115-1-june-2023

This is a minor security (local DoS) upgrade without assigned CVE, so I'll just call it an upgrade but still use it as an excuse for upgrading for 3.18-stable.