Make zhinst dependencies optional and enable python3.10+ compatibility

Explanation of changes

For the user's perspective, we have the following:

for Qblox users:

• nothing breaks, and they can now use python 3.8, 3.9, 3.10, 3.11 and 3.12

for Zhinst users:

• when importing anything zhinst related:
  • if python version >3.9: raise a RuntimeWarning with error message "The zhinst backend is only compatible with Python 3.8 and Python 3.9, but you have Python {major}.{minor}. Please install a compatible python version."
  • if no zhinst dependencies are installed: raise ModuleNotFoundError with error message "The zhinst backend could not be found. Please install the zhinst backend via pip install quantify-scheduler[zhinst]."

pip installs will never complain:

• pip install quantify-scheduler: no longer installs zhinst (and related)
• pip install quantify-scheduler[zhinst]: installs zhinst (and related) only if python_version<3.10.
• pip install quantify-scheduler[dev]: also installs zhinst (and related) only if python_version<3.10.

The last thing makes the pipeline a bit cleaner. We no longer have to create conditional docker images (e.g. explicitly install zhinst for 3.8 and 3.9 tests, but exclude for 3.10+).

Motivation of changes

1. Avoid dependency conflicts in developing the new Zurich Instruments backend (&7)
2. Allow us to support python>=3.10

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Merge checklist

See also merge request guidelines

• Merge request has been reviewed (in-depth by a knowledgeable contributor), and is approved by a project maintainer.
• New code is covered by unit tests (or N/A).
• New code is documented and docstrings use numpydoc format (or N/A).
• New functionality: considered making private instead of extending public API (or N/A).
• Public API changed: added @deprecated and entry in deprecated code suggestions (or N/A).
• Newly added/adjusted documentation and docstrings render properly (or N/A).
• Pipeline fix or dependency update: post in #software-for-developers channel to merge main back in or update local packages (or N/A).
• Tested on hardware (or N/A).
• CHANGELOG.md and AUTHORS.md have been updated (or N/A).
• Performance tests: if changes can affect performance, trigger CI manually and evaluate results (or N/A).
• Windows tests in CI pipeline pass (manually triggered by maintainers before merging).
  • Maintainers do not hit Auto-merge, we need to actively check as manual tests do not block pipeline

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