tests: Simplify Timer utility class

After enabling -Werror for tests, for unknown reasons,
tests/test_wait_signal.py::test_zero_timeout[True] consistently fails on
macOS + Python 3.13 + PySide6 (only there!) with:

    RuntimeWarning: Failed to disconnect (functools.partial(<bound method
    timer.<locals>.Timer._emit of <conftest.Timer(0x...) at 0x...>>,
    <PySide6.QtCore.SignalInstance signal() at 0x...>)) from signal "timeout()".

Qt supports connecting signals to signals, so we can save the detour via Python
and functools.partial.

Author: The-Compiler

tests/conftest.py

@@ -1,4 +1,3 @@
-import functools
 import time
 
 import pytest
@@ -63,10 +62,9 @@ def shutdown(self):
         def single_shot(self, signal, delay):
             t = qt_api.QtCore.QTimer(self)
             t.setSingleShot(True)
-            slot = functools.partial(self._emit, signal)
-            t.timeout.connect(slot)
+            t.timeout.connect(signal)
             t.start(delay)
-            self.timers_and_slots.append((t, slot))
+            self.timers_and_slots.append((t, signal))
 
         def single_shot_callback(self, callback, delay):
             t = qt_api.QtCore.QTimer(self)
@@ -75,9 +73,6 @@ def single_shot_callback(self, callback, delay):
             t.start(delay)
             self.timers_and_slots.append((t, callback))
 
-        def _emit(self, signal):
-            signal.emit()
-
     timer = Timer()
     yield timer
     timer.shutdown()