That isn't even the biggest problem. That breaks, and breakage gets fixed. Other than some slight internal delays there is little harm done. (You have a backup emergency deploy process that doesn't depend on GitHub anyways right?)

The real problem is security vulnerabilities in these pinned dependencies. You end up making a choice between:

1. Pin and risk a malicious update.

2. Don't pin and have your dependencies get out of date and grow known security vulnerabilities.