Validation error for not required inputs that has pattern atribute

[gptforjoomla]

Hi, this pull has a problem with unrequired inputs.

Steps to reproduce the issue

a field that is not required but has pattern to be a number or other . do not fill input and submit.

Expected result

form must submit without error with empty value for the input

Actual result

when user not enter value for this input and submit, validation say that field is not correct

System information (as much as possible)

Joomla 3.8.2

Additional comments

[zero-24]

closing as there is a PR #18624 thanks @minijoomla