Fix healthcheck run spec (#58)

* Add missing return type

* Update CHANGELOG

Author: caike

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Fixed
+
+- Fixed a type mismatch on `Xogmios.HealthCheck.run/1` that was causing a warning on calls to `use Xogmios, :chain_sync`.
+
 ### Added
 
 - Current tip information is now included in the block data passed to `handle_block/2` under the `current_tip` key. This allows clients to calculate the time needed for chainsync to sync from the current position. Adding this to the existing block for now to quickly enable other features, but we should consider implementing a new callback (like `handle_forward/2`) to better handle a new top level entity with both "block" and "tip" as properties.

lib/xogmios/health_check.ex

@@ -6,7 +6,7 @@ defmodule Xogmios.HealthCheck do
 
   @http_client :httpc
 
-  @spec run(url :: String.t()) :: :ok | {:error, String.t()}
+  @spec run(url :: String.t()) :: :ok | {:error, String.t()} | {:incomplete, String.t()}
   def run(ogmios_url) do
     url = parse_url(ogmios_url)