Decrease minimum QProgressDialog duration

We already have a threshold before we use a QProgressDialog at all, so let's
show it quite quickly and not after 4 seconds.

qutebrowser/browser/history.py

@@ -52,6 +52,7 @@ class HistoryProgress:
 
     def start(self, text, maximum):
         self._progress = QProgressDialog()
+        self._progress.setMinimumDuration(500)
         self._progress.setLabelText(text)
         self._progress.setMaximum(maximum)
         self._progress.setCancelButton(None)

tests/unit/browser/test_history.py

@@ -494,6 +494,7 @@ class TestHistoryProgress:
         assert dialog.minimum() == 0
         assert dialog.maximum() == 42
         assert dialog.value() == 1
+        assert dialog.minimumDuration() == 500
 
         progress.finish()
         assert not dialog.isVisible()