Update canonical-data.json

Co-authored-by: Anastasios Chatzialexiou <16361161+tasxatzial@users.noreply.github.com>

Author: ErikSchierboom

exercises/baffling-birthdays/canonical-data.json

@@ -116,7 +116,7 @@
       "description": "has matching birthdays without matching birthday pair",
       "property": "hasMatchingBirthdays",
       "input": {
-        "birthdays": ["1984-04-05", "2000-09-17", "1966-10-12"]
+        "birthdates": ["1984-04-05", "2000-09-17", "1966-10-12"]
       },
       "expected": false
     },