travis/tox: Add PyQt 5.12

See #4478

.travis.yml

@@ -22,6 +22,7 @@ matrix:
     - env: TESTENV=py36-pyqt511-cov
     - python: 3.7
       env: TESTENV=py37-pyqt511
+    - env: TESTENV=py36-pyqt512
     - os: osx
       env: TESTENV=py37 OSX=sierra
       osx_image: xcode9.2

tox.ini

@@ -13,8 +13,8 @@ skipsdist = true
 setenv =
     QT_QPA_PLATFORM_PLUGIN_PATH={envdir}/Lib/site-packages/PyQt5/plugins/platforms
     PYTEST_QT_API=pyqt5
-    pyqt{,56,571,59,510,511}: LINK_PYQT_SKIP=true
-    pyqt{,56,571,59,510,511}: QUTE_BDD_WEBENGINE=true
+    pyqt{,56,571,59,510,511,512}: LINK_PYQT_SKIP=true
+    pyqt{,56,571,59,510,511,512}: QUTE_BDD_WEBENGINE=true
     cov: PYTEST_ADDOPTS=--cov --cov-report xml --cov-report=html --cov-report=
 passenv = PYTHON DISPLAY XAUTHORITY HOME USERNAME USER CI TRAVIS XDG_* QUTE_* DOCKER QT_QUICK_BACKEND
 basepython =
@@ -29,6 +29,7 @@ deps =
     pyqt59: PyQt5==5.9.2
     pyqt510: PyQt5==5.10.1
     pyqt511: PyQt5==5.11.3
+    pyqt512: PyQtWebEngine==5.12
 commands =
     {envpython} scripts/link_pyqt.py --tox {envdir}
     {envpython} -bb -m pytest {posargs:tests}