UPDATE: I've fixed this. I believe the correct way to use it is to put the entire CM under one key. Kind of confusing.

self.argo_configmap = ConfigMap(
            resource_name='test_cm',
            metadata=ObjectMetaArgs(name='argocd-cm',
                                    namespace='argocd'),
            data={
                "repositories": """- type: helm
  url: <https://test.com:8085>
  name: test-helm-repo
  usernameSecret:
      name: test-helm-repo-credentials
      key: username
  passwordSecret:
      name: test-helm-repo-credentials
      key: password
      """
            },

@bumpy-flag-23122 I usually take the data and stringify it to JSON for situations like this