Co-authored-by: Frappe Bot <developers@frappe.io>

* Bumping iPython by a minor version broke 3.6 installs for us via https://github.com/frappe/frappe/pull/14192
* We could just add another line in requirements.txt to solve this, but
  since PY36 is reaching end of life by end of this year and release of
  3.10 is just around the corner, might as well just drop it now than
    later
* Frappe v14 would probably have the support range of 3.7-3.10/11 given
  when we release it. Maintaining dependencies for such a large range
  can become cumbersome

* Remove six for PY2 compatability since our dependencies are not, PY2
  is legacy.
* Removed usages of utils from future/past libraries since they are
  deprecated. This includes 'from __future__ ...' and 'from past...'
  statements.
* Removed compatibility imports for PY2, switched from six imports to
  standard library imports.
* Removed utils code blocks that handle operations depending on PY2/3
  versions.
* Removed 'from __future__ ...' lines from templates/code generators
* Used PY3 syntaxes in place of PY2 compatible blocks. eg: metaclass

recent changes in frappe/__init__.py make use of f-strings that are only
available on python>=3.6

Signed-off-by: Chinmay D. Pai <chinmaydpai@gmail.com>

* fix(unicode): Import unicode_literals in every file

* fix(unicode): Test if safe_json_loads return unicode instead of bytes

- also some spaces and tabs fixes