feat: Make notifier and program async

Using asyncio library, notification are now trigerred
asynchronously.

book_crossfit.py

@@ -2,6 +2,7 @@
 
 import logging
 import traceback
+import asyncio
 from crossfit_booker import CrossFitBooker
 
 if __name__ == "__main__":
@@ -30,5 +31,5 @@ if __name__ == "__main__":
         exit(1)
 
     # Start the continuous booking loop
-    booker.run()
+    asyncio.run(booker.run())
     logging.info("Script completed")