Add datetime.datetime type to commit_date and author_date

Author: SergeantMenacingGarlic

Diff for: git/index/base.py

@@ -4,6 +4,7 @@
 # This module is part of GitPython and is released under
 # the BSD License: http://www.opensource.org/licenses/bsd-license.php
 
+import datetime
 import glob
 from io import BytesIO
 import os
@@ -1032,8 +1033,8 @@ def commit(
         head: bool = True,
         author: Union[None, "Actor"] = None,
         committer: Union[None, "Actor"] = None,
-        author_date: Union[str, None] = None,
-        commit_date: Union[str, None] = None,
+        author_date: Union[datetime.datetime, str, None] = None,
+        commit_date: Union[datetime.datetime, str, None] = None,
         skip_hooks: bool = False,
     ) -> Commit:
         """Commit the current default index file, creating a commit object.

Diff for: git/objects/commit.py

@@ -435,8 +435,8 @@ def create_from_tree(
         head: bool = False,
         author: Union[None, Actor] = None,
         committer: Union[None, Actor] = None,
-        author_date: Union[None, str] = None,
-        commit_date: Union[None, str] = None,
+        author_date: Union[None, str, datetime.datetime] = None,
+        commit_date: Union[None, str, datetime.datetime] = None,
     ) -> "Commit":
         """Commit the given tree, creating a commit object.