Symbols shift back prevention don't work

[epotockiy]

Describe the bug
Tried to updated to newest version of imask but get several unexpected errors, one of it it's not working prevention of shift back functionality for pattern, this functionality can be observed here in demo

To Reproduce
I created playground with code from demo where bug reproduced (example)

Expected behaviour
Prevention of shift back should work the same as for 6 version

Environment:

• react-imask@7.1.3