Broken GHA from forked PRs

[paulb777]

The have_secrets script is failing and causing tests that require secrets to run. See https://github.com/firebase/firebase-ios-sdk/pull/5520/checks?check_run_id=643479328.

It looks like the GITHUB Actions environment variables are no longer including the repo:

++ source scripts/check_secrets.sh
+++ set -x
+++ echo 'GITHUB_BASE_REF: master'
+++ echo 'GITHUB_HEAD_REF: master'
GITHUB_BASE_REF: master
GITHUB_HEAD_REF: master
++ check_secrets

[paulb777]

Actually the problem was not in have_secrets but the gha scripts not checking the environment variable. See #5524.