Update go.skia.org/infra in go.mod/go.sum

To pick up recent changes in buildbot repo for master-> main migration

Updated with:
$ go get go.skia.org/infra@1a8ff8585fce92c0373912c4af385b2e78f5c04b
$ make -C infra/bots train

Bug: skia:11987
Change-Id: Iffa108dff585153c5bf47e709e99d3fa805d6d51
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/409277
Reviewed-by: Eric Boren <borenet@google.com>
Commit-Queue: Ravi Mistry <rmistry@google.com>
3 files changed