Update iqm-client requirement in the python-packages group

Updates the requirements on [iqm-client](https://github.com/iqm-finland/iqm-client) to permit the latest version.

Updates `iqm-client` to 20.9
- [Release notes](https://github.com/iqm-finland/iqm-client/releases)
- [Changelog](https://github.com/iqm-finland/iqm-client/blob/main/CHANGELOG.rst)
- [Commits](iqm-finland/iqm-client@15.2...20.9)

---
updated-dependencies:
- dependency-name: iqm-client
  dependency-type: direct:production
  dependency-group: python-packages
...

Signed-off-by: dependabot[bot] <[email protected]>

setup.py

@@ -42,7 +42,7 @@
     license="Apache 2",
     packages=find_namespace_packages(include=["pytket.*"]),
     include_package_data=True,
-    install_requires=["pytket >= 1.33.0", "iqm-client ~= 15.2"],
+    install_requires=["pytket >= 1.33.0", "iqm-client >= 15.2,< 21.0"],
     classifiers=[
         "Environment :: Console",
         "Programming Language :: Python :: 3.10",