Overall, I am against this specific action move because it introduces maintenance/comprehension overheads without enough gain and because it makes support for Squid-version-specific dependencies a lot more difficult/cumbersome, negating many of the benefits of an invasive CI configuration file. However, I do not plan on vetoing this PR on these grounds.

PR description: [Squid] workflow file can use actions defined in this repository

Action reuse is indeed possible, but, AFAICT, the changes in this PR do not create a reusable action. If you insist on moving this dependency installation code into a different repository, then please follow GitHub requirements for creating reusable actions. When you are done, please test reuse using your /squid and /ci repository clones on GitHub and share a pointer to that test.