BUMP 4.15.4.dev0

Signed-off-by: mongodb-dbx-release-bot[bot] <167856002+mongodb-dbx-release-bot[bot]@users.noreply.github.com>

Author: mongodb-dbx-release-bot[bot]

pymongo/_version.py

@@ -18,7 +18,7 @@
 import re
 from typing import List, Tuple, Union
 
-__version__ = "4.15.3"
+__version__ = "4.15.4.dev0"
 
 
 def get_version_tuple(version: str) -> Tuple[Union[int, str], ...]: