Fix test expectations for .gitignore comment created by Python 3.13+ venv

Since Python 3.13, the .gitignore file is created by venv:
python/cpython#108125

Fixes pypa#2670

Author: hroncok

tests/unit/create/test_creator.py

@@ -217,7 +217,11 @@ def list_to_str(iterable):
         assert result == "None"
 
     git_ignore = (dest / ".gitignore").read_text(encoding="utf-8")
-    assert git_ignore.splitlines() == ["# created by virtualenv automatically", "*"]
+    if creator_key == "venv" and sys.version_info >= (3, 13):
+        comment = "# Created by venv; see https://docs.python.org/3/library/venv.html"
+    else:
+        comment = "# created by virtualenv automatically"
+    assert git_ignore.splitlines() == [comment, "*"]
 
 
 def test_create_vcs_ignore_exists(tmp_path):