Always clear searches between page loads

Looks like this wasn't properly fixed in Qt for some reason.
Fixes #3693
See #2728 and bef372e5f5

doc/changelog.asciidoc

@@ -97,6 +97,7 @@ Fixed
 ~~~~~
 
 - Various subtle keyboard focus issues.
+- Workaround for a Qt bug which preserves searches between page loads.
 
 Removed
 ~~~~~~~

qutebrowser/browser/webengine/webenginetab.py

@@ -1137,10 +1137,9 @@ class WebEngineTab(browsertab.AbstractTab):
     @pyqtSlot()
     def _on_load_started(self):
         """Clear search when a new load is started if needed."""
-        if (qtutils.version_check('5.9', compiled=False) and
-                not qtutils.version_check('5.9.2', compiled=False)):
         # WORKAROUND for
         # https://bugreports.qt.io/browse/QTBUG-61506
+        # (seems to be back in later Qt versions as well)
         self.search.clear()
         super()._on_load_started()
         self.data.netrc_used = False