Feature: Make pizza oven service deployable/buildable to 32 bit systems

[jpmcb]

Currently, the minimum free disk env variable is parsed as uint64:

https://github.com/open-sauced/pizza/blob/51ed9ca9798ad3f9c39fc02a368fc1f525949737/main.go#L71-L78

This is mostly fine since I'd imagine we're only going to deploy this to 64 bit systems.

A stretch goal / nice to have someday would be to make this dynamic for the system that is being compiled to. I think this would be a simple check against bits.UintSize (which should be set at compile time).

The tricky part will be cross building images on different machines with the right bit lengths.

But again, I anticipate only really needing 64 bit systems, so this is a stretch goal.