Use datetime.now instead of current_datetime

The `microseconds=True` argument to `current_datetime` makes it
equivalent to the much shorter and standard `datetime.now(tz=UTC)`.
Use the standard construction and reserve `current_datetime` for
the cases where we want to suppress the microseconds field.

tests/handlers/api_tokens_test.py

@@ -943,7 +943,7 @@ async def test_create_admin(
     # Intentionally pass in a datetime with microseconds. They should be
     # stripped off so that the expiration is rounded to seconds, which we will
     # check when examining the log message.
-    now = current_datetime(microseconds=True)
+    now = datetime.now(tz=UTC)
     expires = now + timedelta(days=2)
     caplog.clear()
     r = await client.post(

tests/support/logging.py

@@ -7,7 +7,6 @@
 from typing import Any
 
 import pytest
-from safir.datetime import current_datetime
 
 __all__ = ["parse_log"]
 
@@ -33,7 +32,7 @@ def parse_log(
         List of parsed JSON dictionaries with the common log attributes
         removed (after validation).
     """
-    now = current_datetime(microseconds=True)
+    now = datetime.now(tz=UTC)
     messages = []
 
     for log_tuple in caplog.record_tuples: