title: ERROR: Could not build wheels for opencv-python which use PEP 517 and cannot be installed directly
body: <p>I was trying to install OpenCV4 in a docker on jetson nano. It has jetpack 4.4 s os. The docker was successfully created and Tensorflow is running but while installing OpenCV using pip it is showing CMake error.</p>
  <pre><code>root@5abf405fb92d:~# pip3 install opencv-python
  Collecting opencv-python
    Downloading opencv-python-4.4.0.42.tar.gz (88.9 MB)
       |████████████████████████████████| 88.9 MB 2.5 kB/s 
    Installing build dependencies ... done
    Getting requirements to build wheel ... done
      Preparing wheel metadata ... done
  Requirement already satisfied: numpy&gt;=1.13.3 in /usr/local/lib/python3.6/dist-packages (from opencv-python) (1.18.4)
  Building wheels for collected packages: opencv-python
    Building wheel for opencv-python (PEP 517) ... error
    ERROR: Command errored out with exit status 1:
     command: /usr/bin/python3 /usr/local/lib/python3.6/dist-packages/pip/_vendor/pep517/_in_process.py build_wheel /tmp/tmpqpzwrofy
         cwd: /tmp/pip-install-93nxibky/opencv-python
    Complete output (9 lines):
      File &quot;/tmp/pip-build-env-o_hualnr/overlay/lib/python3.6/site-packages/skbuild/setuptools_wrap.py&quot;, line 560, in setup
        cmkr = cmaker.CMaker(cmake_executable)
      File &quot;/tmp/pip-build-env-o_hualnr/overlay/lib/python3.6/site-packages/skbuild/cmaker.py&quot;, line 95, in __init__
        self.cmake_version = get_cmake_version(self.cmake_executable)
      File &quot;/tmp/pip-build-env-o_hualnr/overlay/lib/python3.6/site-packages/skbuild/cmaker.py&quot;, line 82, in get_cmake_version
        &quot;Problem with the CMake installation, aborting build. CMake executable is %s&quot; % cmake_executable)
    Traceback (most recent call last):
    
    Problem with the CMake installation, aborting build. CMake executable is cmake
    ----------------------------------------
    ERROR: Failed building wheel for opencv-python
  Failed to build opencv-python
  ERROR: Could not build wheels for opencv-python which use PEP 517 and cannot be installed directly
  </code></pre>