security/archlinux-keyring: limit to Python 3.10 and later

libkeyringctl/trust.py includes Structural Pattern Matching (PEP-636)
introduced in Python 3.10.

https://gitlab.archlinux.org/archlinux/archlinux-keyring/-/merge_requests/267
(cherry picked from commit 7a11a9f2280f0e1639e869af59c436e255a7fa74)