PY-24182 Fixed: datetime.isoformat(timespec='seconds') argument is not recognized as valid

Add `timespec` parameter to `datetime.datetime.isoformat` pyi-stub for Python 3.6+.

python/helpers/typeshed/stdlib/3/datetime.pyi

@@ -1,7 +1,7 @@
 # Stubs for datetime
 
 # NOTE: These are incomplete!
-
+import sys
 from typing import Optional, SupportsAbs, Tuple, overload
 
 MINYEAR = 0
@@ -202,7 +202,10 @@ class datetime:
                 Optional[_tzinfo] = None) -> datetime: ...
     def astimezone(self, tz: Optional[_tzinfo] = ...) -> datetime: ...
     def ctime(self) -> str: ...
-    def isoformat(self, sep: str = ...) -> str: ...
+    if sys.version_info >= (3, 6):
+        def isoformat(self, sep: str = ..., timespec: str = ...) -> str: ...
+    else:
+        def isoformat(self, sep: str = ...) -> str: ...
     @classmethod
     def strptime(cls, date_string: str, format: str) -> datetime: ...
     def utcoffset(self) -> Optional[timedelta]: ...

python/testData/typeshed/stdlib/3/datetime_test.py

@@ -178,6 +178,7 @@ def test_timedelta():
 
 def test_datetime():
     from datetime import datetime, timedelta, date, time
+    import sys
 
     datetime(2000, 12, 25)
     datetime(2000, 12, 25, 23)
@@ -220,6 +221,11 @@ def test_datetime():
     assert dt.timetz() == time(23, 59, 59)
     assert dt.ctime() == "Mon Dec 25 23:59:59 2000"
     assert dt.isoformat() == "2000-12-25T23:59:59"
+    assert dt.isoformat(' ') == "2000-12-25 23:59:59"
+    assert dt.isoformat(sep=' ') == "2000-12-25 23:59:59"
+    if sys.version_info >= (3, 6):
+        assert dt.isoformat(' ', 'minutes') == "2000-12-25 23:59"
+        assert dt.isoformat(sep=' ', timespec='minutes') == "2000-12-25 23:59"
     assert dt.utcoffset() is None
     assert dt.tzname() is None
     assert dt.dst() is None