chore: use timezone aware object

Signed-off-by: Henry Schreiner <[email protected]>

Author: henryiii

pyproject.toml

@@ -150,6 +150,7 @@ extend-select = [
     "PERF", # perflint
     "ARG", # flake8-unused-arguments
     "C4", # flake8-comprehensions
+    "DTZ", # flake8-datetimez
     "EM", # flake8-errmsg
     "ICN", # flake8-import-conventions
     "G", # flake8-logging-format

src/mplhep/_dev.py

@@ -544,7 +544,9 @@ def _run_benchmarks(self, baseline_name: str | None = None) -> bool:
             self._print_success(f"Will save benchmark results as: {baseline_name}")
         else:
             # Auto-generate baseline name with timestamp
-            timestamp = datetime.datetime.now().strftime("%Y%m%d_%H%M%S")
+            timestamp = datetime.datetime.now(tz=datetime.timezone.utc).strftime(
+                "%Y%m%d_%H%M%S"
+            )
             baseline_name = f"run_{timestamp}"
             cmd.append(f"--benchmark-save={baseline_name}")
             self._print_success(f"Will save benchmark results as: {baseline_name}")