Add CI for tests

[josh146]

[josh146]

Tests are currently failing with

module 'qsharp' has no attribute 'clients'

🤔

[josh146]

Update: more tests are now passing. The failing tests seem to be a combination of:

     self.measure += self._observable_map[e.name].format(wires=device_wires.tolist())
E   ValueError: Single '}' encountered in format string

 /github/home/.local/lib/python3.7/site-packages/pennylane/_device.py:290: in execute
    self.post_apply()
/github/home/.local/lib/python3.7/site-packages/pennylane_qsharp/device.py:145: in post_apply
    self.qs = qsharp.compile(self._source_code)
/usr/local/lib/python3.7/site-packages/qsharp/__init__.py:60: in compile
    for op in client.compile(code)
E   TypeError: 'NoneType' object is not iterable

as well as a few stochastic failures.

Edit: tests take 2.5 hours to run 😱

[antalszava]

[ch2856]