updated package setup (#485)

* updated package setup

* updated to use python 3.9

* fixed test runner

* fixed typecheck tests

* fixed discrepencies

* added override to runner

* updated travis

* updated pre-commit hooks

* updated dep

pyproject.toml

@@ -1,3 +1,8 @@
 [tool.black]
 line-length = 120
-include = 'django-stubs/.*\.pyi$'
+include = '\.pyi?$'
+
+[tool.isort]
+line_length = 120
+multi_line_output = 3
+include_trailing_comma = true