Deprecation warning for setting float type to QDialog size hint

When running the test suite of `etsdemo` with Python 3.8 and PyQt 5.15, I got the following warnings:
```
/Users/kchoi/Work/ETS/venvs/etsdemo-test/lib/python3.8/site-packages/traitsui/qt4/ui_base.py:191: DeprecationWarning: an integer is required (got type float). Implicit conversion to integers using __int__ is deprecated, and may be removed in a future version of Python.
size.setWidth(view.width)
/Users/kchoi/Work/ETS/venvs/etsdemo-test/lib/python3.8/site-packages/traitsui/qt4/ui_base.py:193: DeprecationWarning: an integer is required (got type float). Implicit conversion to integers using __int__ is deprecated, and may be removed in a future version of Python.
size.setHeight(view.height)
```

Package version info:
```
Package Version
---------- -------------
configobj 5.0.6
docutils 0.16
eam 1.1.0
etsdemo 0.1.0.dev1554
pip 19.2.3
pyface 7.0.1
Pygments 2.6.1
PyQt5 5.15.0
PyQt5-sip 12.8.0
setuptools 41.2.0
six 1.15.0
traits 6.1.1
traitsui 7.0.1
```