Fix failing check_pki_certs test
Unit tests are failing (as they will annually) for check_pki_certs,
which is run against the airsloop site in the treasuremap repo. Similar
to the change last year [0], this updates the treasuremap ref to the tip
of the v1.9 branch, which includes new certs for airsloop [1], seaworthy
[2], and seaworthy-virt [3] sites.
Change-Id: Ibfcdde11a35ed2207e78c2d2f372ab2d2e1f2e63
0: https://review.opendev.org/c/airship/pegleg/+/729269
1: https://review.opendev.org/c/airship/treasuremap/+/789482
2: https://review.opendev.org/c/airship/treasuremap/+/789483
3: https://review.opendev.org/c/airship/treasuremap/+/789484
2a0519e397