Fixing Qiskit tests, outstanding deprecations and warnings

[KilianPoirier]

Description

• Several changes are included in this PR:

  • Resolution of the version incompatibility between Qiskit and Azure
  • Update of the tests for Qiskit >=0.45.0
  • Removed a lot of deprecated expressions in openqaoa-qiskit
  • Changed plotting functions to remove warnings

• Incompatibility with Qiskit and Azure versioning made installation impossible.

• **Fixes pip install openqaoa throws some qiskit error #296 **

Checklist

• I have performed a self-review of my code.
• I have commented my code and used numpy-style docstrings
• I have made corresponding updates to the documentation.
• My changes generate no new warnings
• New and existing unit tests pass locally with my changes.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)