[Cashtab] Update dep script

Summary:
chronik-client is a dev dep of ecash-lib as it uses the type to run the integration tests

So, we need to build chronik-client before we can build ecash-lib

Test Plan: ./install-deps

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D18525