TimestampStrings allows ZoneInfo object as time_zone parameter

So we can use pre-parsed data

Some tests for parsing settings, timestamp output

src/corelibs/string_handling/timestamp_strings.py

@@ -23,11 +23,13 @@ class TimestampStrings:
 
     TIME_ZONE: str = 'Asia/Tokyo'
 
-    def __init__(self, time_zone: str | None = None):
+    def __init__(self, time_zone: str | ZoneInfo | None = None):
         self.timestamp_now = datetime.now()
         self.time_zone = time_zone if time_zone is not None else self.TIME_ZONE
         try:
-            self.timestamp_now_tz = datetime.now(ZoneInfo(self.time_zone))
+            self.timestamp_now_tz = datetime.now(
+                ZoneInfo(self.time_zone) if not isinstance(self.time_zone, ZoneInfo) else self.time_zone
+            )
         except ZoneInfoNotFoundError as e:
             raise ValueError(f'Zone could not be loaded [{self.time_zone}]: {e}') from e
         self.today = self.timestamp_now.strftime('%Y-%m-%d')