Shopify-python

Bump latest version to 0.5.3 (https://github.com/Shopify/shopify_python/pull/113)

Bugfixes:
- Pin astroid dependency to fix failing tests (https://github.com/Shopify/shopify_python/pull/112)
- Gate typing package to `< 3.7` (https://github.com/Shopify/shopify_python/pull/112)

Checks added :

- Forbid Sequence[str] 94

Checks added :

- Check for blank line after a class definition 86

Bugfixes:

- Bump GitPython to 2.1.8 87
- Astroid less than 1.6 89
- Fix the crash on Autopep8 breaking change 91

Bugfix release that includes these bugfixes:

- Lambda_func and operators (83)

Bugfix release that includes these bugfixes:
- Add support for 'is' keyword https://github.com/Shopify/shopify_python/pull/79