-> !pip install opencv-python (https://pypi.org/project/opencv-python/)
-> !pip install dlib (https://pypi.org/project/dlib/)
-> !pip install face-recognition (https://pypi.org/project/face-recognition/)
-> !pip install numpy (https://pypi.org/project/numpy/)
NOTE: dlib is a package that supports the face_recognition package, so it is essential to install dlib first, and then face_recognition.
NOTE: dlib installation is different for every OS, hance a standard Requirements file was not possible.