Error message provided via function not being returned in validation errors when using .matches()

[KeelanM90]

Describe the bug
As of version 0.28.4 the default error message is returned when a function is provided for the message param in string.matches() rather than the given message within the function

To Reproduce
https://codesandbox.io/s/eager-leftpad-sbpxk?file=/src/index.test.js

Expected behavior
As per prior versions, expect to pass a function that returns a string and be provided with the given message in the event of an error

Platform (please complete the following information):

• Browser Chrome
• Version 80

Additional context
Aim to provide a PR to fix this