Flag in deploy to specify --no-deps

[plutonium-239]

Since package size is limited, it would be great if we could have an option of pip install with --no-deps, probably at the time of deta deploy?
i.e. the requirements.txt file we provide would be considered "complete", and no other dependencies would be installed.

Coming from #621.

[plutonium-239]

@aavshr @rabingaire
Do you think this would be possible? (asking you considering you both have committed to the cli a lot)