Pytket-iqm

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* Updated pytket version requirement to 1.23.
* Add some additional post-routing optimisations to the default compilation pass for `optimisation_level=2`.
* Updated iqm-client version requirement to 15.2.

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* Updated pytket version requirement to 1.22.

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* Don't include ``SimplifyInitial`` in default passes; instead make it an option
to ``process_circuits()``.
* Updated pytket version requirement to 1.21.

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* Update pytket version requirement to 1.20.
* Update iqm-client version requirement to 14.0.
* Fix job status checks.
* Add support for token-based authentication.

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* Updated pytket version requirement to 1.13.
* Updated iqm-client version requirement to 11.8.
* New method ``IQMBackend.get_metadata()`` for reteieving metadata associated
with a ``ResultHandle``.

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* Updated iqm-client version requirement to 9.1.
* IQMBackend initializer now does not accept a settings file.
* IQMBackend initializer now retrieves device name and qubit names from backend
server instead of configuration file.
* IQMBackend initializer now retrieves qubit coupling (connectivity) and native
gateset from backend server instead of hard-coded constants.
* Updated pytket version requirement to 1.8.