Hide SetProcessDpiAwareness Qt warning.

This shows up on AppVeyor CI for some reason.
See https://bugreports.qt.io/browse/QTBUG-38993

qutebrowser/utils/log.py

@@ -285,6 +285,8 @@ def qt_message_handler(msg_type, context, msg):
         'QXcbWindow: Unhandled client message: "_E_',
         'QXcbWindow: Unhandled client message: "_ECORE_',
         'QXcbWindow: Unhandled client message: "_GTK_',
+        # Happens on AppVeyor CI
+        'SetProcessDpiAwareness failed:',
     )
     if any(msg.strip().startswith(pattern) for pattern in suppressed_msgs):
         level = logging.DEBUG

tox.ini

@@ -162,4 +162,6 @@ pep8ignore =
     resources.py ALL
 mccabe-complexity = 12
 qt_log_level_fail = WARNING
-qt_log_ignore = ^SpellCheck: .*
+qt_log_ignore =
+    ^SpellCheck: .*
+    ^SetProcessDpiAwareness failed: .*