Missing AWS creds cause Digger to fail PR check even if no projects affected

[ZIJ]

1. Create PR that does not affect any projects without configuring AWS keys for Digger
2. Digger run fails (as expected)
3. Create secrets for creds
4. Comment "digger plan"

Expected: plan check updated

Actual: plan check stays failed

Example PR: diggerhq/quickstart-actions-aws#3