Don't pass argument to cocotb.triggers.Event.set()

The argument to cocotb.triggers.Event.set() was not documented and ended
up being removed from upcoming cocotb 2.0 release. Unfortunately it was
exposed to the users of Monitor, thus for now we simply set the .data
attribute that Event no longer has any support for. This can be removed
on next API break.

src/cocotb_bus/monitors/__init__.py

@@ -50,7 +50,10 @@ class Monitor:
 
     def __init__(self, callback=None, event=None):
         self._event = event
+        if self._event is not None:
+            self._event.data = None  # FIXME: This attribute should be removed on next API break
         self._wait_event = Event()
+        self._wait_event.data = None
         self._recvQ = deque()
         self._callbacks = []
         self.stats = MonitorStatistics()
@@ -106,7 +109,7 @@ async def wait_for_recv(self, timeout=None):
         else:
             await self._wait_event.wait()
 
-        return self._wait_event.data
+        return self._wait_event_data
 
     # this is not `async` so that we fail in `__init__` on subclasses without it
     def _monitor_recv(self):
@@ -132,11 +135,13 @@ def _recv(self, transaction):
             self._recvQ.append(transaction)
 
         if self._event is not None:
-            self._event.set(data=transaction)
+            self._event.set()
+            self._event.data = transaction
 
         # If anyone was waiting then let them know
         if self._wait_event is not None:
-            self._wait_event.set(data=transaction)
+            self._wait_event.set()
+            self._wait_event.data = transaction
             self._wait_event.clear()