fix: restore Actor.name_email_regex (#2220)

GitPython 3.1.60 removed the Actor.name_email_regex class attribute while replacing internal actor parsing, which broke downstream consumers such as python-semantic-release.

Restore the historical compiled pattern as a compatibility API while leaving Actor._from_string on its linear delimiter parser. The regression covers the public match behavior and verifies the parser remains independent of the regex, preserving the GHSA-g5vv-9gxw-82hx fix.

Validation:
- test/test_actor.py and actor-related test/test_util.py cases: 12 passed
- ruff check and format checks passed

Author: codex

git/util.py

@@ -858,6 +858,8 @@ class Actor:
     committers and authors or anything with a name and an email as mentioned in the git
     log entries."""
 
+    name_email_regex = re.compile(r"(.*) <(.*?)>")
+
     # ENVIRONMENT VARIABLES
     # These are read when creating new commits.
     env_author_name = "GIT_AUTHOR_NAME"

test/test_actor.py

@@ -3,6 +3,8 @@
 # This module is part of GitPython and is released under the
 # 3-Clause BSD License: https://opensource.org/license/bsd-3-clause/
 
+from unittest import mock
+
 from git import Actor
 
 from test.lib import TestBase
@@ -29,10 +31,15 @@ def test_from_string_should_handle_just_name(self):
 
     def test_from_string_handles_unterminated_email_without_regex_backtracking(self):
         value = "A" * 20_000 + " <unterminated"
-        actor = Actor._from_string(value)
-        self.assertNotIn("name_email_regex", vars(Actor))
+        with mock.patch.object(Actor, "name_email_regex", None):
+            actor = Actor._from_string(value)
         self.assertEqual(actor, Actor(value, None))
 
+    def test_name_email_regex_is_available(self):
+        match = Actor.name_email_regex.match("Michael Trier <mtrier@example.com>")
+        self.assertIsNotNone(match)
+        self.assertEqual(match.groups(), ("Michael Trier", "mtrier@example.com"))
+
     def test_from_string_does_not_parse_across_lines(self):
         self.assertEqual(Actor._from_string("x <a>\n y <b>"), Actor("x", "a"))