[infra] Pin infra code using Go modules

Change-Id: I005740aef6ab8ba78f3da4d3b9d744ce3fb326e6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/211982
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Ben Wagner aka dogben <benjaminwagner@google.com>
Commit-Queue: Eric Boren <borenet@google.com>
26 files changed