[3.11] gh-115403: Remove extra colon after "Examples" in datetime documentation (GH-115452) (#115456)

gh-115403: Remove extra colon after "Examples" in datetime documentation (GH-115452)
(cherry picked from commit 6755c4e)

Co-authored-by: Stanislav Lyu <[email protected]>

Author: miss-islington

Doc/library/datetime.rst

@@ -1777,7 +1777,7 @@ Other constructor:
       be truncated).
    4. Fractional hours and minutes are not supported.
 
-   Examples::
+   Examples:
 
    .. doctest::