conan2 support
https://github.com/conan-io/conan/releases/tag/2.0.0 released Feb 22, 2023.

It introduces a few problems:
1. `conan download` now requires `-r conancenter`
2. `conan download catch2/3.0.1@:a25d6c83542b56b72fdaa05a85db5d46f5f0f71c -r conancenter` returns `ERROR: 404: Not Found. [Remote: conancenter]`
3. The fetched packages stores the .hpp files in `~/.conan2` instead of `~/.conan/`

The cause is that finding these .hpp files is hard coded in
https://github.com/py2many/py2many/blob/280fbe5/pycpp/__init__.py#L14-L18