update missing timestap

Author: pjbull

cloudpathlib/http/httppath.py

@@ -1,3 +1,4 @@
+import datetime
 import http
 import os
 from pathlib import Path, PurePosixPath
@@ -112,7 +113,9 @@ def stat(self, follow_symlinks: bool = True) -> os.stat_result:
                 None,  # gid,
                 meta.get("size", 0),  # size,
                 None,  # atime,
-                meta.get("last_modified", 0).timestamp(),  # mtime,
+                meta.get(
+                    "last_modified", datetime.datetime.fromtimestamp(0)
+                ).timestamp(),  # mtime,
                 None,  # ctime,
             )
         )