pyproject: move mypy config to pyproject.toml

Signed-off-by: Filipe Laíns <lains@riseup.net>

Author: FFY00

pyproject.toml

@@ -65,5 +65,10 @@ max-complexity = 10
 lines-between-types = 1
 lines-after-imports = 2
 
+[tool.mypy]
+python_version = '3.9'
+strict = true
+show_error_codes = true
+
 [tool.coverage.html]
 show_contexts = true