cluster_name and profile are terraform variables

resource "null_resource" "oidc_provider" {
  triggers = {
    cluster_name = var.cluster_name
  }

  provisioner "local-exec" {
    command = <<EOF
AWS_PROFILE=${var.profile} eksctl utils associate-iam-oidc-provider --cluster ${var.cluster_name} --approve
EOF
  }
}

Check result with command

aws iam list-open-id-connect-providers | jq ".OpenIDConnectProviderList[].Arn"