some fixes again

python_app/storage/npz/store.py

@@ -3,7 +3,7 @@
 from __future__ import annotations
 
 from contextlib import suppress
-from datetime import datetime
+from datetime import datetime, timezone
 import json
 from pathlib import Path
 from typing import Any
@@ -162,7 +162,7 @@ class NpzStore(StoreApi):
             raise ValueError("last_n must be > 0")
 
         output_dir.mkdir(parents=True, exist_ok=True)
-        timestamp = datetime.utcnow().strftime("%Y%m%d_%H%M%S")
+        timestamp = datetime.now(timezone.utc).strftime("%Y%m%d_%H%M%S")
         snapshot_dir = output_dir / f"snapshot_{timestamp}"
         snapshot_dir.mkdir(parents=True, exist_ok=True)
 
@@ -184,7 +184,7 @@ class NpzStore(StoreApi):
         if last_n <= 0:
             raise ValueError("last_n must be > 0")
 
-        snapshot_stem = snapshot_name.strip() or datetime.utcnow().strftime("snapshot_%Y%m%d_%H%M%S")
+        snapshot_stem = snapshot_name.strip() or datetime.now(timezone.utc).strftime("snapshot_%Y%m%d_%H%M%S")
         snapshot_stem = sanitize_path_component(snapshot_stem)
 
         output_root_dir.mkdir(parents=True, exist_ok=True)
@@ -237,7 +237,7 @@ class NpzStore(StoreApi):
         if last_n <= 0:
             raise ValueError("last_n must be > 0")
 
-        output_stem = output_name.strip() or datetime.utcnow().strftime("snapshot_%Y%m%d_%H%M%S")
+        output_stem = output_name.strip() or datetime.now(timezone.utc).strftime("snapshot_%Y%m%d_%H%M%S")
         output_stem = sanitize_path_component(output_stem)
 
         output_root_dir.mkdir(parents=True, exist_ok=True)
@@ -299,7 +299,7 @@ class NpzStore(StoreApi):
         if last_n <= 0:
             raise ValueError("last_n must be > 0")
 
-        output_stem = output_name.strip() or datetime.utcnow().strftime("snapshot_%Y%m%d_%H%M%S")
+        output_stem = output_name.strip() or datetime.now(timezone.utc).strftime("snapshot_%Y%m%d_%H%M%S")
         output_stem = sanitize_path_component(output_stem)
         output_root_dir.mkdir(parents=True, exist_ok=True)
         output_dir = self._vna_json_output_dir(output_root_dir, output_stem)