title: pip install PyQt6 fails: module 'sipbuild.api' has no attribute 'prepare_metadata_for_build_wheel'
body: <p>Installing PyQt6 on a Linux Mint box fails with this error:</p>
  <pre><code>AttributeError: module 'sipbuild.api' has no attribute 'prepare_metadata_for_build_wheel'
  </code></pre>
  <p>The same error is mentioned in several posts, sometimes for PyQt6,  sometimes for other modules.  However,  none of the proposed solutions (like upgrading pip) seems to work.</p>
  <p>Any suggestions on how to figure out what is wrong?</p>
  <p>Below are the commands I used.  Installation is in a virtual environment (but installing it on the main machine results in the same error).</p>
  <pre><code>johan@morla:~/work\&gt; cat /etc/issue
  Linux Mint 19 Tara \n \l
  
  johan@morla:~/work\&gt; python --version
  Python 3.9.12
  johan@morla:~/work\&gt; python -m venv env
  johan@morla:~/work\&gt; . env/bin/activate
  johan@morla:~/work\&gt; pip list
  Package    Version
  ---------- -------
  pip        22.1
  setuptools 58.1.0
  johan@morla:~/work\&gt; pip install PyQt6
  Collecting PyQt6
    Using cached PyQt6-6.3.0-cp37-abi3-manylinux1_x86_64.whl (7.8 MB)
  Collecting PyQt6-sip&lt;14,&gt;=13.2
    Using cached PyQt6_sip-13.3.1-cp39-cp39-manylinux1_x86_64.whl (306 kB)
  Collecting PyQt6
    Using cached PyQt6-6.2.3-cp36-abi3-manylinux1_x86_64.whl (7.7 MB)
    Using cached PyQt6-6.2.2-cp36-abi3-manylinux1_x86_64.whl (7.7 MB)
    Using cached PyQt6-6.2.1-cp36-abi3-manylinux1_x86_64.whl (7.7 MB)
    Using cached PyQt6-6.2.0.tar.gz (1.0 MB)
    Installing build dependencies ... done
    Getting requirements to build wheel ... done
    Preparing metadata (pyproject.toml) ... error
    error: subprocess-exited-with-error
    
    × Preparing metadata (pyproject.toml) did not run successfully.
    │ exit code: 1
    ╰─&gt; [33 lines of output]
        Querying qmake about your Qt installation...
        /usr/bin/qmake -query
        Traceback (most recent call last):
          File &quot;/home/johan/work/env/lib/python3.9/site-packages/pip/_vendor/pep517/in_process/_in_process.py&quot;, line 156, in prepare_metadata_for_build_wheel
            hook = backend.prepare_metadata_for_build_wheel
        AttributeError: module 'sipbuild.api' has no attribute 'prepare_metadata_for_build_wheel'
  </code></pre>