updated travis build to latest pytest

Author: nicoddemus

.travis.yml

@@ -10,8 +10,8 @@ virtualenv:
 env:
  - PYTEST_VERSION=2.5.2 PYTEST_QT_FORCE_PYQT=true
  - PYTEST_VERSION=2.5.2 PYTEST_QT_FORCE_PYQT=false
- - PYTEST_VERSION=2.6.0 PYTEST_QT_FORCE_PYQT=true
- - PYTEST_VERSION=2.6.0 PYTEST_QT_FORCE_PYQT=false
+ - PYTEST_VERSION=2.6.3 PYTEST_QT_FORCE_PYQT=true
+ - PYTEST_VERSION=2.6.3 PYTEST_QT_FORCE_PYQT=false
 
 install:
  - sudo apt-get update