This updates python extension to a version supporting only python3.

To have full python2 support, it's possible to download
https://open-vsx.org/extension/ms-python/python/2020.10.332292344
and use "Install from VSIX" option and manually apply the patch to fix
perfomance issue with buildout paths:

    curl https://lab.nexedi.com/nexedi/slapos/raw/bdb7777beb34d8840cbbc498adba7a55d521079b/component/theia/ms-python-disable-jedi-buildout.patch | patch  ~/tmp/vscode-unpacked/ms-python.python-2020.10.332292344.vsix/extension/pythonFiles/lib/python/jedi/inference/sys_path.py