Get rid of six package in docs and setup.py

.github/workflows/build-docs.yml

@@ -20,7 +20,7 @@ jobs:
       - name: Install dependencies
         run: | 
           sudo apt-get update
-          sudo apt-get install -y build-essential libeigen3-dev libyaml-dev libfftw3-dev libavcodec-dev libavformat-dev libavutil-dev libswresample-dev libsamplerate0-dev libtag1-dev libchromaprint-dev python3-dev python3-numpy-dev python3-numpy python3-yaml python3-six
+          sudo apt-get install -y build-essential libeigen3-dev libyaml-dev libfftw3-dev libavcodec-dev libavformat-dev libavutil-dev libswresample-dev libsamplerate0-dev libtag1-dev libchromaprint-dev python3-dev python3-numpy-dev python3-numpy python3-yaml
           sudo apt-get install -y doxygen python3-pip pandoc
           pip3 install sphinx pyparsing sphinxcontrib-doxylink docutils jupyter sphinxprettysearchresults sphinx-toolbox
           # Install TensorFlow

doc/sphinxdoc/installing.rst

@@ -55,7 +55,7 @@ You can install those dependencies on a Debian/Ubuntu system from official repos
 
 In order to use Python 3 bindings for the library, you might also need to install python3-dev, python3-numpy-dev (or python3-numpy on Ubuntu) and python3-yaml for YAML support in python::
 
-  sudo apt-get install python3-dev python3-numpy-dev python3-numpy python3-yaml python3-six
+  sudo apt-get install python3-dev python3-numpy-dev python3-numpy python3-yaml
 
 Note that, depending on the version of Essentia, different versions of ``libav*`` and ``libtag1-dev`` packages are required. See `release notes for official releases <https://github.com/MTG/essentia/releases>`_.
 

doc/sphinxdoc/machine_learning.rst

@@ -59,7 +59,7 @@ Install the `dependencies <https://essentia.upf.edu/installing.html#installing-d
 
 .. code-block::
 
-    apt-get install build-essential libyaml-dev libfftw3-dev libavcodec-dev libavformat-dev libavutil-dev libavresample-dev python-dev libsamplerate0-dev libtag1-dev libchromaprint-dev python-six python3-dev python3-numpy-dev python3-numpy python3-yaml libeigen3-dev
+    apt-get install build-essential libyaml-dev libfftw3-dev libavcodec-dev libavformat-dev libavutil-dev libavresample-dev python-dev libsamplerate0-dev libtag1-dev libchromaprint-dev python3-dev python3-numpy-dev python3-numpy python3-yaml libeigen3-dev
 
 Configure Essentia with TensorFlow and Python 3:
 

setup.py

@@ -103,7 +103,7 @@ def get_version():
 Website: https://essentia.upf.edu
 '''
 
-setup_requires = ['numpy>=1.8.2', 'six']
+setup_requires = ['numpy>=1.8.2']
 install_requires = setup_requires + ['pyyaml']
 
 # Require tensorflow for the package essentia-tensorflow