Add channel measurement endpoint

[ldecicco-USGS]

Basically this is a learning experience for me on how to follow the waterdata patterns.

This PR adds a function get_channel to access:
https://api.waterdata.usgs.gov/ogcapi/v0/collections/channel-measurements/items

The corresponding R function is here:
https://doi-usgs.github.io/dataRetrieval/reference/read_waterdata_channel.html
https://github.com/DOI-USGS/dataRetrieval/blob/main/R/read_waterdata_channel.R

Things to note that I'll want to learn about from one of you eventually:
I'm trying to use Positron - I've more or less switched over to it for R development, and it feels like a good Python environment, but I know I'm 100% biased.

I switched my settings so that the ruff formatter would automatically format on save. When I did that I got HUNDREDS of tiny style updates (end of lines, moving number of spaces, trailing commas). I undid those changes so I'm not pushing those here. I did not edit the pyproject.toml. So, either there are lots of automatic formatting issues we could push up, or my setup is different and I should learn how to get it working the same as the rest of you.

The other thing is when I ran the tests I had 10 failed tests - non of which are in the "waterdata_test". So not sure if I've got some setting wrong or if we have some failing tests (but they aren't related to the channel measurement test I added).

[thodson-usgs]

The relevant test passes. Ignore the other CI failures.