adding "knative-gcp/test/conflict/" to the white list of callers for the shell package

[cathyzhyi]

I am trying to add an e2e test to detect knative-gcp overwriting other installed components google/knative-gcp#1995. This will need to read the output of ko apply and look for the word configured. It would convenient if I can use the shell package.

Is it OK to just add the path to

hack/shell/project.go

Line 68 in d946d25

validPaths := []string{

or is there any suggestions on how should I do this?