Figure out dependency best practices

### What problem are you facing?

This SDK is a library. It has some dependencies (e.g. gRPC, Click, etc) but I assume we don't want to pin them to specific versions - instead the app would do that. Right now I have everything "pinned" to major versions only. We're also declaring that we only work with Python 3.11, since it's what the https://github.com/GoogleContainerTools/distroless container we'll use to run Python functions uses.

### How could this Function help solve your problem?

My Python packaging experience is almost a decade out-of-date so I'm not sure what the best practice is here. I could use a review from folks with more recent Python library packaging experience.