When I access the URL from here, the SSL certificate is not expired. I would suggest to retry the command now to see if it works.
If you still get the same error, I would check the date & time settings on your computer - they might be incorrect.
If they're correct, I would suggest manually installing the program. The Cask code for this specific app is very simple, so you can easily do it manually.
Simply open this URL in a browser:
Download the DMG file for macOS. Double-click the DMG to open it, and install like any other application.
UPDATE: Given the comment below that the question was not asked for the purpose of getting NetLogo installed, but rather to understand why the problem occurs and how to resolve it properly:
When you look closer at the TLS communication with the download server (ccl.northwestern.edu), we see that the problem is actually with the bundled intermediate certificates. I.e. the actual certificate for ccl.northwestern.edu is OK and not expired, however the server replies with a number of intermediates and CA certificates that are expired (in particular the "USERTrust RSA Certification Authority" and "AddTrust Extdernal CA Root" certificates).
When you access the site in Safari, you do not get an error, as it uses macOS' built-in certificate store. In Keychain you can validate that macOS by default has an up to date and non-expired CA certificate for "USERTrust RSA Certification Authority". Therefore you do not get any errors here.
However when you use
brew-cask, the file is downloaded using
curl - and
curl does not access the same trust store. If you try to download the file manually on the command line using
curl -O you'll get the same error.
The client-side fix for the
curl command line is to set
CURL_CA_BUNDLE environment to point to a text file that has the updated intermediates. I've tested that and you can then download without warnings.
brew-cask does not seem to relay that environment variable on to
curl, nor does it seem to respect a
cacert line in ~/.curlrc.
The optimal way to resolve this problem is to fix the server. Update the intermediate certificate bundle associated with the web site on the server, and the problem will go away.