Add a projector observable to QiskitDevice

[wongwsvincent]

Context:
Adding a projector observable to QiskitDevice.

Description of the Change:
Adding Projector to the list of observables compatible with QiskitDevice in qiskit_device.py.

Related GitHub PR:
Work coherently with PR #1356

[josh146]

Thanks @wongwsvincent 🙂

This looks great, and likely doesn't need a unit test (unlike the Cirq device) since there is no new logic here.

I do have one question though, how come you added docstrings to some of the inherited methods? Not having docstrings here was intentional, since Sphinx will instead insert the docstrings from the parent class. This reduces the maintainability overhead :)

[josh146]

💪

[codecov]

Codecov Report

Merging #137 (97e0b11) into master (5793462) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #137   +/-   ##
=======================================
  Coverage   99.29%   99.29%           
=======================================
  Files           7        7           
  Lines         284      284           
=======================================
  Hits          282      282           
  Misses          2        2           

Impacted Files	Coverage Δ
pennylane_qiskit/qiskit_device.py	100.00% <100.00%> (ø)

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[wongwsvincent]

@josh146 , I added docstrings here because I saw CodeFactor in the github workflow was complaining about not having docstrings under the functions. I'm not sure why the docstrings weren't inherited from the parent class, and I'm not familiar enough with Sphinx to understand why. The flagged issues can be found here.

Could you give me a bit of help here?

[josh146]

I saw CodeFactor in the github workflow was complaining about not having docstrings under the functions

Thanks for flagging this @wongwsvincent --- it appears that Codefactor is incorrect here, and these particular methods do not need docstrings.

Feel free to remove them, even if codefactor complains about the missing docstrings, I will be able to overwrite those :)

[wongwsvincent]

Thanks for clarifying, @josh146 ! I have removed the docstrings.

[josh146]

Thanks @wongwsvincent! Good to go now 💯