Update 3.13.0 expected release date (#1427)

Author: ned-deily

include/release-cycle.json

@@ -11,7 +11,7 @@
     "branch": "3.13",
     "pep": 719,
     "status": "prerelease",
-    "first_release": "2024-10-01",
+    "first_release": "2024-10-07",
     "end_of_life": "2029-10",
     "release_manager": "Thomas Wouters"
   },