resolve method
Used to resolve the auth using the getSecret function.
Implementation
@override
ResolvedAuth resolve(String? Function(String name) getSecret) {
  final secret = getSecret(secretName);
  if (secret == null) {
    throw MissingSecretsException(this);
  }
  return switch (sendIn) {
    ApiKeyLocation.header => ResolvedAuth(
      headers: {name: secret},
      params: const {},
    ),
    ApiKeyLocation.query => ResolvedAuth(
      headers: const {},
      params: {name: secret},
    ),
  };
}