Packages are built from source on RPi instead of a wheel installation

Expected behaviour

Installed OpenCV on Raspberry Pi 4 using a wheel, but not from source.

Actual behaviour

When the opencv-python package is installing on RPi it usually builds from source using opencv-python-4.5.3.56.tar.gz instead of a wheel (e.g. opencv_python-4.5.3.56-cp36-cp36m-manylinux2014_aarch64.whl)

Steps to reproduce

• Example code:

python3 -m pip install --no-cache --force-reinstall opencv-python==4.5.3.56

• operating system: Raspbian GNU/Linux 10 (buster)
• opencv-python version: 4.5.3.56

Issue submission checklist

• This is not a generic OpenCV usage question (looking for help for coding, other usage questions, homework etc.)
• I have read the README of this repository and understand that this repository provides only an automated build toolchain for OpenCV Python packages (there is no actual OpenCV code here)
• The issue is related to the build scripts in this repository, to the pre-built binaries or is a feature request (such as "please enable this additional dependency")
• I'm using the latest version of opencv-python