Don't run submodule update workflow on forks (#1183)
Don't run submodule update workflow on forks (#1183)

This would be really annoying and is totally unnecessary. I don't want a PR every day from everyone's fork :-D

Tested:
Tried this out in my fork, both filtering to my fork repository (https://github.com/GMNGeoffrey/iree/runs/522552789) and filtering to the main repository (https://github.com/GMNGeoffrey/iree/actions/runs/59835678)
google/iree,google/iree,iree-org/iree,google/iree,iree-org/iree,iree-org/iree,google/iree,iree-org/iree,iree-org/iree,iree-org/iree,iree-org/iree,google/iree,google/iree,google/iree