pub async fn is_active<T: TokenClient>(&self, client: &T) -> Result<bool, Error> {
        let metadata = self.fetch_metadata(client).await?;
        let current_time = current_unix_time();
        let active = is_token_active(&metadata, current_time);
        Ok(active)
    }
Checks if the token is active. We do a few checks:
1. Fetch the token metadata.
2. From the metadata, check if the token is active.
3. If the token is a SAML SSO token, check if it's expired.
crates/turborepo-auth/src/lib.rs