add mypy config matching precommit

mypy.ini

@@ -1,4 +1,14 @@
 [mypy]
 python_version = 3.8
-ignore_missing_imports = True
 plugins = numpy.typing.mypy_plugin
+
+; third-party packages
+ignore_missing_imports = True
+
+; helpful warnings
+warn_redundant_casts = True
+warn_unreachable = True
+warn_unused_ignores = True
+
+; restrict dynamic typing
+warn_return_any = True