Make sure that build-images workflow has permissions to read PR info (#24897)
Make sure that build-images workflow has permissions to read PR info (#24897)

For a public repo this information is public so no extra permission is
required, but just in case this workflow ends up against a private repo
we need these permissions explicitly.
apache/airflow,cfei18/incubator-airflow,nathanielvarona/airflow,cfei18/incubator-airflow,nathanielvarona/airflow,cfei18/incubator-airflow,danielvdende/incubator-airflow,apache/airflow,danielvdende/incubator-airflow,apache/airflow,apache/airflow,nathanielvarona/airflow,danielvdende/incubator-airflow,danielvdende/incubator-airflow,cfei18/incubator-airflow,cfei18/incubator-airflow,danielvdende/incubator-airflow,apache/airflow,nathanielvarona/airflow,danielvdende/incubator-airflow,apache/airflow,cfei18/incubator-airflow,nathanielvarona/airflow,nathanielvarona/airflow