use CDN to determine availability of newer conda-smithy

The check for being up-to-date with the smithy version seems to go to the package server directly, which leads to the following failure (for the hour or so that the package makes its way through the CDN, during which time the newer version is not actually installable yet!):

RuntimeError: conda-smithy version (3.10.2) is out-of-date (3.10.3) in conda-smithy's environment. Exiting.

That hour is not the most critical thing in the world (though it can be painful when suddenly you cannot rerender just as you need it), but now there was an unlucky confluence of events - basically 3.10.3 was uploaded to the server after https://github.com/conda-forge/status/issues/115 hit the CDN, and until this is resolved, it’s impossible to actually install the package and therefore to do any local rerenders.

Ideally, the check should be changed to use the same channel-data as the conda-installer, so that such situations cannot happen again.

[isuruf]

Maybe we should add that option to the error message.

[isuruf]

It’s not impossible. You can do conda-smithy rerender --no-check-uptodate to make the error go away.