add mypy config file

Author: herobank110

mypy.ini

@@ -0,0 +1,9 @@
+[mypy]
+files = src,tests
+no_implicit_optional = True
+pretty = True
+show_error_codes = True
+strict_equality = True
+warn_redundant_casts = True
+warn_unused_configs = True
+warn_unused_ignores = True