Use CURL debug callback function to log with spdlog?

[wolfv]

In mamba, we've recently started to route verbose CURL output through spdlog thanks to the debug callback:

https://github.com/mamba-org/mamba/blob/e5bb726e02a948f8e97e69a1e371dde6e8824823/libmamba/src/core/fetch.cpp#L218-L237

https://github.com/mamba-org/mamba/blob/e5bb726e02a948f8e97e69a1e371dde6e8824823/libmamba/src/core/fetch.cpp#L267-L269