Generate constraints in PRs when upgrading dependencies (#20624)
Generate constraints in PRs when upgrading dependencies (#20624)

The constraints generation was only happening in push/scheduled
runs, but sometimes it is useful to check what constraints would
be generated even in the PRs that change setup.py/setup.cfg

The change causes constraint generation also in the PRs and only
pushing the updated constraints is not executed in PRs.
nathanielvarona/airflow,Acehaidrey/incubator-airflow,nathanielvarona/airflow,Acehaidrey/incubator-airflow,apache/airflow,danielvdende/incubator-airflow,bolkedebruin/airflow,apache/airflow,nathanielvarona/airflow,bolkedebruin/airflow,lyft/incubator-airflow,danielvdende/incubator-airflow,nathanielvarona/airflow,apache/airflow,Acehaidrey/incubator-airflow,apache/airflow,bolkedebruin/airflow,Acehaidrey/incubator-airflow,cfei18/incubator-airflow,danielvdende/incubator-airflow,cfei18/incubator-airflow,mistercrunch/airflow,apache/airflow,cfei18/incubator-airflow,lyft/incubator-airflow,cfei18/incubator-airflow,apache/airflow,nathanielvarona/airflow,Acehaidrey/incubator-airflow,nathanielvarona/airflow,cfei18/incubator-airflow,mistercrunch/airflow,bolkedebruin/airflow,cfei18/incubator-airflow,lyft/incubator-airflow,Acehaidrey/incubator-airflow,mistercrunch/airflow,lyft/incubator-airflow,mistercrunch/airflow,danielvdende/incubator-airflow,danielvdende/incubator-airflow,bolkedebruin/airflow,danielvdende/incubator-airflow