fix endpoint health

PythonServer/pos-python-server.py

@@ -4,6 +4,7 @@ import epics
 import time
 import requests
 from fastapi import FastAPI
+from fastapi.responses import PlainTextResponse
 import dateutil.parser
 import datetime
 from epicsarchiver import ArchiverAppliance
@@ -23,7 +24,7 @@ executor = ThreadPoolExecutor(max_workers=10)
 
 @app.get("/-/health")
 async def heath():
-    return "OK"
+    return PlainTextResponse("OK")
 
 
 @app.get("/api/v1/caget/{pvlist}")