Set user agent header when making API requests

[zeke]

The user agent for requests from this library are currently defaulting to something like python-requests/2.27.1. This PR updates the client to set a user agent header in the form replicate-python@<version>, so we can more easily identify where our API traffic is coming from.

[zeke]

Hmm. This worked locally but I guess putting the version in the replicate directory won't work because then setup tries to load replicate/__init__.py?

Looks like there a ton of hacky ways to get around this.. not sure which one is least offensive.

[bfirsh]

We also probably want to set __version__ = package_version in replicate/__init__.py. That's a standard location for Python package versions.

[zeke]

Like this? 5aa9b3f

[bfirsh]

Nope -- you can just do from .package_version import package_version.

[zeke]

Ah I see. It's only setup.py that can't safely do import.

[zeke]

This is ready for another look.

[bfirsh]

As an aside package_version is a bit weird -- I've never seen that before. It's either in package/__init__.py or in package/version.py.

We could move the other version.py out of the way (into models/?) or rename to _version.py.

This pattern's rather nice, with __about__.py:

https://github.com/pypa/warehouse/blob/64ca42e42d5613c8339b3ec5e1cb7765c6b23083/warehouse/__about__.py
https://github.com/pypa/warehouse/blob/64ca42e42d5613c8339b3ec5e1cb7765c6b23083/warehouse/__init__.py

We'll also want to rename package_version = ... in the file to __version__ = ... so we can import it directly.

[zeke]

Updated it to use __about__. This is ready for another look.

[bfirsh]

Marvellous!