Use correct timezone to compare step scheduling

`get_last_workflow_invocation_step_update_time()` returns UTC time (it's
set by galaxy.model.orm.now.now()) while datetime.now() is your local
time.

If your system is not on UTC time this caused 5 minute scheduling delays
for steps depending on expression tools that only produce parameters.

Fixes the delay observed in https://github.com/galaxyproject/tools-iuc/pull/7314

lib/galaxy/model/orm/now.py

@@ -1,4 +1,7 @@
-from datetime import datetime
+from datetime import (
+    datetime,
+    timezone,
+)
 
 # NOTE REGARDING TIMESTAMPS:
 #   It is currently difficult to have the timestamps calculated by the
@@ -7,7 +10,12 @@ from datetime import datetime
 #   relies on the client's clock being set correctly, so if clustering
 #   web servers, use a time server to ensure synchronization
 
-# Return the current time in UTC without any timezone information
-now = datetime.utcnow
+
+def now():
+    """
+    Return the current time in UTC without any timezone information.
+    """
+    return datetime.now(timezone.utc).replace(tzinfo=None)
+
 
 __all__ = ("now",)

lib/galaxy/workflow/scheduling_manager.py

@@ -12,6 +12,7 @@ import galaxy.workflow.schedulers
 from galaxy import model
 from galaxy.exceptions import HandlerAssignmentError
 from galaxy.jobs.handler import InvocationGrabber
+from galaxy.model.orm.now import now
 from galaxy.schema.invocation import (
     FailureReason,
     InvocationFailureDatasetFailed,
@@ -341,12 +342,12 @@ class WorkflowRequestMonitor(Monitors):
                 invocation_step_update_time := invocation.get_last_workflow_invocation_step_update_time()
             ):
                 do_schedule = invocation_step_update_time > last_schedule_time
-            if not do_schedule and (datetime.now() - last_schedule_time) > self.timedelta:
+            if not do_schedule and (now() - last_schedule_time) > self.timedelta:
                 # If we haven't scheduled in a while, schedule anyway.
                 log.debug(
                     "Scheduling workflow invocation [%s] after %s seconds without scheduling.",
                     invocation.id,
-                    (datetime.now() - last_schedule_time).total_seconds(),
+                    (now() - last_schedule_time).total_seconds(),
                 )
                 do_schedule = True
             return do_schedule
@@ -449,7 +450,7 @@ class WorkflowRequestMonitor(Monitors):
                         if i.active and i.id < workflow_invocation.id:
                             return False
                 if self.ready_to_schedule_more(workflow_invocation):
-                    self.update_time_tracking_dict[invocation_id] = datetime.now()
+                    self.update_time_tracking_dict[invocation_id] = now()
                     workflow_scheduler.schedule(workflow_invocation)
                     log.debug("Workflow invocation [%s] scheduled", invocation_id)
             except Exception: