NAN is sometimes used by some programmers when numpy was 1.x but now on 2.x the caps version is disallowed.

Added the caps conversion to lower case nan to fix that automatically.

Source:
https://numpy.org/doc/2.0/reference/constants.html?utm_source=chatgpt.com
NaN and NAN are aliases of nan.

freqtrade/strategy/strategyupdater.py

@@ -46,6 +46,7 @@ class StrategyUpdater:
             "aliases": set(),
             "replacements": [
                 ("NaN", "nan"),
+                ("NAN", "nan"),
             ],
         }
     }