cenpy-devs/cenpy: Product API

This release adds the long-running product API, which adds a direct interface to the US Census Bureau using placenames.

In addition to a ton of work on the product API, a number of bugs, issues, and enhancements were added.

1. docstrings were improved and made more consistent throughout the library.
2. a website (cenpy-devs.github.io/cenpy) was built to house the documentation for the package, alongside use cases that show how users can access the product API and developers can build on top of the cenpy primitives to make their own products.
3. error handling for requests was improved in cases of choppy or filtered internet connections.
4. a bug in the geometry requests was fixed.
5. variable filter/searching was improved, in filter_variables (cenpy.products) or varslike (cenpy.remote)
6. tests were improved & continuous integration updated to take into account better defaults in conda-forge