fix(python): use print for the startup message, not log.critical

logging.critical is used to convey serious error situations. Some services set
alerts on critical messages, so the use of log.critical for startup confuses
them.

python/src/wslink/backends/aiohttp/__init__.py

@@ -23,7 +23,7 @@
 
 async def _on_startup(app):
     # Emit an expected log message so launcher.py knows we've started up.
-    logging.critical("wslink: Starting factory")
+    print("wslink: Starting factory")
     # We've seen some issues with stdout buffering - be conservative.
     sys.stdout.flush()