Where to put a new certificate .cer file so that ddev composer will use it instead of the default one?

I am using WSL2 with Ubuntu following the instructions here: https://ddev.readthedocs.io/en/stable/users/quickstart/#drupal

➜  my-drupal10-site2 ddev composer create drupal/recommended-project
Executing Composer command: [composer create-project drupal/recommended-project --no- 
   install /tmp/hwdqJW]

Creating a "drupal/recommended-project" project at "/tmp/hwdqJW"
Installing drupal/recommended-project (10.2.4)
  - Downloading drupal/recommended-project (10.2.4)
  - Downloading drupal/recommended-project (10.2.4)
  - Downloading drupal/recommended-project (10.2.4)
  - Downloading drupal/recommended-project (10.2.4)
    Failed to download drupal/recommended-project from dist: curl error 60 while 
downloading https://api.github.com/repos/drupal/recommended- 
  project/zipball/b4d1be6b9682e27a6adc430ad08a14745d0b67ff: SSL certificate problem: 
  self signed certificate in certificate chain
Now trying to download from source

I have a .cer cert file that is supposed to fix this. where do I put this file so that it used that so I don’t get a self-signed certificate error? When I test this file using the following command:

openssl s_client -connect api.github.com:443 -CAfile /home/snrub/mycert-base64.cer 

…it works great! However, if I run this command:

openssl s_client -connect api.github.com:443

…it fails with a self-signed certificate error. So I just need to know where to put that .cer file.