Automated Update-Multiple-Repo solutions?

Looking for advice/help.

I have a whole suite of django applications (20+) that are internal tools for my company.
We will frequently have code changes (maintenance, security, best practice standards etc.) that we will need to apply to all 20+. This means we have to repeat the same change 20+ times.

Does anyone know of any existing solution that would help or do I have to start from scratch?