Deprecate and point to upstream ical

Author: hugovk

README.md

@@ -1,7 +1,9 @@
 # python-release-schedule-ical
 
+> [!WARNING]
+> This repo's ical file is deprecated and will be removed in the future. Use https://peps.python.org/release-schedule.ics instead.
+
 This tool generates a calendar with future milestones of multiple versions of Python. The data are extracted from PEPs and the calendar is updated daily.
-You can subscribe to it using this link:                                                                                                                                                         https://github.com/fedora-python/python-release-schedule-ical/raw/master/python-releases.ics
 
 ## License
 Autogenerated calendar and all code in this repository is dedicated to the public domain under the