Fix remaining tests

For some reason the pytest vscode integration has stopped discovering tests, so I didn't know some were failing until GH actions
ran them. Oops.

Author: Crozzers

test/test_common.py

@@ -274,13 +274,15 @@ def test_returns_most_recent_window(self, snapshots: list[Snapshot]):
 
             window = snapshot.history[-1].windows[0]
             other_window = snapshot.history[0].windows[0]
-            lkp = snapshot.last_known_process_instance(window.executable)
+            lkp = snapshot.last_known_process_instance(window)
 
             assert lkp is window
             assert lkp is not other_window
 
         def test_returns_none_if_window_not_found(self, snapshots: list[Snapshot]):
-            assert snapshots[0].last_known_process_instance('does not exist') is None
+            window = deepcopy(snapshots[0].history[0].windows[0])
+            window.executable = 'does-not-exist.exe'
+            assert snapshots[0].last_known_process_instance(window) is None
 
         class TestMatchTitleKwarg:
             @pytest.fixture