Potential fix for pull request finding

Update the docstring to match the real response type.

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: ebertin

src/visiomatic/server/app.py

@@ -202,10 +202,8 @@ async def get_health():
 
         Returns
         -------
-        response:  byte stream
-            Returns "ok" string if server is alive.
-        """
-        return {"ok": True}
+        response: dict
+            Returns {"ok": True} if server is alive.
 
 
     # Tile endpoint