tox: Update pytest-qt to 1.5.0.

Upstream changelog:

* Fixed log line number in messages, and provide better contextual information
  in Qt5 (#55, thanks @The-Compiler);
* Fixed issue where exceptions inside a `waitSignals` or `waitSignal`
  with-statement block would be swallowed and a `SignalTimeoutError` would be
  raised instead. (#59, thanks @The-Compiler for bringing up the issue and
  providing a test case);
* Fixed issue where the first usage of `qapp` fixture would return `None`.
  Thanks to @gqmelo for noticing and providing a PR;
* New `qtlog` now sports a context manager method, `disabled` (#58). Thanks
  @The-Compiler for the idea and testing;

tox.ini

@@ -24,7 +24,7 @@ deps =
     py==1.4.30
     pytest==2.7.2
     pytest-capturelog==0.7
-    pytest-qt==1.4.0
+    pytest-qt==1.5.0
     pytest-mock==0.6.0
     pytest-html==1.3.1
 commands =